Dissertations / Theses on the topic 'Screening Mammography'

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
"June 2017." Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 37).
Breast cancer is the most common cancer among women worldwide. Today, the vast majority of breast cancers are diagnosed from screening mammography. Multiple randomized clinical studies have demonstrated that screening mammography can help reduce the number of deaths from breast cancer among women ages 40 to 74, especially for those over age 50 [4], and can provide women diagnosed with breast cancer more options for less aggressive treatment [7]. Screening mammography is the first entry into the funnel of clinical mammography. A screening mammogram can result in a suspicious finding, leading the patient to receive additional imaging, and even surgical biopsy if the additional imaging. Screening mammography, as the first part of this funnel, is a place for machine learning to have impact on the largest amount of patients. In this work, we apply machine learning models to tasks in clinical mammography such as density estimation, and Bi-Rads prediction.
by Nicholas Locascio.
M. Eng.

Les cancers du sein peuvent être classifiés selon le statut de récepteur d’estrogène (RE), de récepteur de progestérone (RP), de récepteur HER2, ou selon quatre sous-types (Luminal A, Luminal B, HER2-enrichi, Triple-négatif) ayant des propriétés biologiques et cliniques différentes. La sensibilité du dépistage par mammographie pourrait varier selon ces types de cancers mais ceci n’est pas encore clair. L’agressivité de la tumeur, mesurée par le grade histologique pourrait expliquer cette association. Les types de cancers d’intervalle ont été comparés à ceux de cancers détectés par dépistage parmi 1536 cas infiltrants provenant d’un centre de référence de Québec. Les tumeurs RE-négatif, RP-négatif, HER2-positif, Luminal B, HER2-enrichi et TPN étaient tous plus fréquentes chez les femmes avec cancers d’intervalle que chez celles avec cancers détectés par dépistage. À l’exception des tumeurs HER2-positif et HER2-enrichi, le grade histologique expliquait en grande partie la variabilité observée entre les types de cancer et la sensibilité.
Breast cancers can be classified according to tumour estrogen (ER) and progesterone (PR) receptors, human epidermal growth factor receptor 2 (HER2), and according to four subtypes (Luminal A, Luminal B, HER2-enriched, Triple-negative), each with different biological and clinical profiles. These tumour types may also influence screening mammography sensitivity but this is still not clear. Tumour aggressiveness, measured by the histological grade, may also play a role in explaining this association. Interval cancer types were compared to screen-detected cancer types in 1536 invasive cases obtained from a reference center in Quebec. ER-negative, PR-negative and HER2-positive, Luminal B, HER2-enriched and TPN tumours were all more frequent in women with interval cancers than in women with screen-detected cancers. Except for HER2-positive and HER2-enriched tumours, histological grade explained most of the variability observed between tumour receptor status, subtypes and sensitivity.

This work includes a series of studies that examines the health and economic impacts of screening mammography from international and Canadian perspectives. This work is a compendium of several researched chapters that include an introduction, four body chapters, and a discussion. The body chapters include a systematic review of the health economic literature on screening mammography, a review of quantitative models used to examine the consequences of breast cancer screening, and cost-effectiveness analyses of screening mammography programs in Canada for the general female population and for subgroups of the population at high-risk for breast cancer. There are three analytic chapters that will be submitted as manuscripts for peer-reviewed publication. The main results of this research show that current screening mammography practices in Canada may extend life at an acceptable cost to the health care system. Due to the outlined methodological limitations of this research the results should be interpreted with caution.

Background and Objectives: When the benefits and risks of mammography are considered, the risk of radiation-induced cancer is calculated only for the breast using the mean glandular dose (MGD). Whilst MGD is a useful concept, it has many limitations. This thesis aims to establish a novel method to determine and convey radiation risk from full field digital mammography (FFDM) screening using lifetime effective risk. Method: For effective risk calculations, organ doses as well as examined breast MGD are required. Screening mammography was simulated by exposing a breast phantom for cranio-caudal and medio-lateral oblique for each breast using 16 FFDM machines. An anthropomorphic dosimetry phantom loaded with thermo-luminescent detectors (TLDs) was positioned in contact with the breast phantom to simulate the client’s body. Once the risk per individual was calculated, total effective lifetime risk across 48 worldwide screening programmes was calculated. The total effective risk data sets were analysed to establish a regression model to predict the effective risk of any screening programme. Graphs were generated to extrapolate the total effective risk of any screening programme of specific screening commencement age and frequency considering the MGD differences of different FFDM machines. Since the highest radiation dose after examined breast was received by contralateral breast, the effect of a contralateral breast lead shield on effective risk was also investigated. Results: Large differences in the effective lifetime risk exist between worldwide screening programmes. The effective lifetime risk varied from approximately 50 cases/106 to more than 1000 cases/106. These differences were mainly attributed to the commencement age and frequency of screening. Since tissue radio-sensitivity reduces with age, the cessation age of screening mammography does not result in a noteworthy effect on the total effective risk. The use of contralateral breast shield reduces the total effective risk by about 1.5% for most worldwide screening programmes. Conclusion: A novel method has been proposed to assess radiation-induced cancer risk from FFDM screening which considers the radiation dose received by all body tissues in addition to the examined breast. Using effective risk, the data is more likely to be understandable by screening clients and referring clinicians, unlike MGD which is not readily available or understandable by the general populace. This novel method and the data are compatible with the incoming European Commission legislation about giving the patient information on radiation risk.

X-ray mammography is the imaging modality of choice in screening to detect breast cancer in its early stages. In recent years, film-screen systems have been replaced by various digital mammography technologies as these can deliver better performance than conventional film-screen technology. However, it remains unclear how the physical performance of such systems and the choice of their operating parameters is correlated with the ,ability to detect early breast cancer. While clinical trials are used to address this issue, they have many associated limitations such as unethical extra exposure, time consuming data collection and completion of trials. Alternatively, a simulation framework whereby suitably realistic synthetic breast cancer pathology is inserted into normal clinical mammograms to form a large database can enable a more efficient comparison of multiple systems and study of technical parameters which influence the detection task. This thesis presents a novel computational model of breast mass appearance using fractal growth which can exhibit a range of lesion appearances. Masses generated using Random Walk (RW) and Diffusion Limited Aggregation (DLA) models were inserted into raw digital 2D mammograms using a physical model of the imaging process, thus avoiding ad hoc post-processing of the final image. The simulation framework accounted for local glandularity, polychromatic X-ray spectra, image degradation caused by the imaging system acquisition process, scatter and finally processing with manufacturer's image processing software to produce realistic lesion attenuation and contrast. An ROe study of realism gave an average AUC and corresponding 95% CIs of 0.55 (0.51, 0.59) for DLA masses. This suggests that the DLA approach appears to produce a more realistic range of mass appearances compared to the RW approach, which achieved an AUC of 0.60 (0.56, 0.63). Both results demonstrate improvement compared to previously published ROe studies of realism of the simulated masses. The mass simulation models may be used subsequently as part of a tool to evaluate different breast imaging technologies (2D and 3D) and their performance in the detection task. Digital breast tomosynthesis (DBT) may have superior performance compared to 2D mammography in terms of cancer visibility, especially in dense breasts. Lesions grown using the DLA method, previously validated in 2D mammograms, were used to simulate breast masses into clinical DBT projection images. A pilot study was performed where radiologists feedback suggests that DLA masses can be successfully embedded in DBT projections and can produce visually authentic DBT images containing synthetic pathology. However, mass appearance whilst entirely satisfactory in 2D, does not always reliably infer satisfactory appearance in DBT.

Purpose: The purpose of this thesis is to understand the relationship between mammographic performance based on actual clinical reading and performances at screen read test-sets, as well as to examine the potential causal agents for any lack of correlation. Methods: This study was designed to encompass three facets. The first element investigated the extent to which test-set reading can represent actual clinical reporting in screening mammography. The second element examined the manner that the location where reading takes place and the availability of prior images can impact upon performance in breast test-set reading. The third element considered the reading workstation monitors and the viewing environment available within BreastScreen New South Wales centres to determine whether consistent reporting conditions were provided to breast screen readers. Results: Moderate or acceptable level of agreement (W = 0.69–0.73, P < 0.01) were shown between actual clinical reporting and test-set conditions when describing group performance. The agreement was enhanced when prior images were available. The location where reading takes place and the availability of prior images showed acceptable levels of agreement (W = 0.75–0.79, P < 0.001) between group performance although both factors had a varying impact when examining the results of individual reader. The final aspect demonstrated an overall good adherence of reading workstation monitors and the viewing environment to published guidelines. Conclusions: Test-set readings in clinical and laboratory settings can be used to represent radiologic group performance in the clinic to a reasonable level particularly if prior images are available. If individual efficacy is being examined, some observers do demonstrate differences between test-sets and clinical performance, as well as differences between test-set situations even when viewing conditions are generally adhering to international standards.

Having a high recall rate may increase the probability of cancer being detected earlier, however it also has been related to increased false positive decisions, causing significant psychological and economical costs for both screened women and the mammography screening service. Therefore, the purpose of this thesis is to explore the impact of various recall rates on breast radiologists’ performance in a laboratory setting. Methods This study was designed to encompass two aspects 1) the effect of setting varying recall rates on the performance of breast radiologists in screening mammography 2) types of mammographic appearances of breast cancer are more likely to be missed at different recall rates. Five Australian breast radiologists were recruited to read one single test set of 200 mammographic cases (180 normal and 20 abnormal cases) over three different recall rate conditions: free recall, 15% and 10%. These radiologists were tasked with marking the location of suspicious lesions and providing a confidence. Results A significant decrease in radiologists’ performance was observed when reading at lower recall rates, with lower sensitivity (P=0.002), case location sensitivity (P=0.002) and ROC AUC (P=0.003). Reading at a lower recall rate had a significant increase in specificity (P=0.002). The second study of this thesis showed that breast radiologists demonstrated lower sensitivity and receiver ROC AUC for non-specific density (NSD) (P=0.04 and P=0.03 respectively) and mixed features (P=0.01 and P=0.04 respectively) when reading at 15% and 10% recall rates. No significant change was observed on cancer characterized with stellate masses (P=0.18 and P=0.54 respectively) and architectural distortion (P=1.00 and P=0.37 respectively). Conclusion Reducing the number of recalled cases to 10% significantly reduced breast radiologists’ performance. Stellate masses were likely to be recalled (90.0%) while NSDs were likely to be missed (45.6%) at reduced recall rates.

The first aim of the research was to determine the applicability of certain variables from the Health Belief Model (HBM), the Theory of Reasoned Action (TRA), the risk dimensions from the Psychometric Paradigm, the Common-Sense Model of Illness Representations and the Locus of Control to Italian women’s beliefs and behaviours in relation to screening mammography. These models have predominantly been derived and evaluated with English-speaking persons. The study used quantitative and qualitative methods to enable explanation of research-driven and participant-driven issues. The second aim was to include Italian women in health behaviour research and to contrast the Italian sample with the Anglo-Australian sample to determine if differences exist in relation to their beliefs. In Australia many studies in health behaviour research do not include women whose first language is not English. The third aim was to evaluate the Anti-Cancer Council of Victoria’s (ACCV) Community Language Program (CLP) by: (a) identifying the strengths and weaknesses of the program as seen by the participants; and (b) assessing the impact of the program on women’s knowledge and beliefs about breast cancer, early detection of breast cancer, self-reported and intended breast screening behaviours. The CLP is an information service that uses women’s first language to convey information to women whose first language is not English. The CLP was designed to increase knowledge about breast and cervical cancer. The research used a pre-test-intervention-post-test design with 174 Italian-born and 138 Anglo-Australian women aged 40 years and over. Interviews for the Italian sample were conducted in Italian. The intervention was an information session that related to breast health and screening mammography. Demographic variables were collected in the Pre-Test only. Qualitative open-ended questions that related specifically to the information session were collected in the Post-Test phase of the study. Direct logistic regression was used with the participants’ beliefs and behaviours to identify the relevant variables for language (Italian speaking and English-speaking), attendance to an information session, mammography screening and breast self-examination (BSE) behaviour. Pre- and Post-Test comparisons were conducted using chi-square tests for the non-parametric data and paired sample t-tests for the parametric data. Differences were found between the Italian and Anglo-Australian women in relation to their beliefs about breast cancer screening. The Italian women were: (1) more likely to state that medical experts understood the causes of breast cancer; (2) more likely to feel that they had less control over their personal risk of getting breast cancer; (3) more likely to be upset and frightened by thinking about breast cancer; (4) less likely to perceive breast cancer as serious; (4) more likely to only do what their doctor told them to do; and (5) less likely to agree that there were times when a person has cancer and they don’t know it. A pattern emerged for the Italian and Anglo-Australian women from the logistic regression analyses. The Italian women were much more likely to comply with medical authority and advice. The Anglo-Australian women were more likely to feel that they had some control over their health. Specifically, the risk variable ‘dread’ was more applicable to the Italian women’s behaviour and internal locus of control variable was more relevant to the Anglo-Australian women. The qualitative responses also differed for the two samples. The Italian women’s comments were more general, less specific, and more limited than that of the Anglo-Australian women. The Italian women talked about learning how to do BSE whereas the Anglo-Australian women said that attending the session had reminded them to do BSE more regularly. The key findings and contributions of the present research were numerous. The focus on one cultural group ensured comprehensive analyses, as did the inclusion of an adequate sample size to enable the use of multivariate statistics. Separating the Italian and Anglo-Australian samples in the analyses provided theoretical implications that would have been overlooked if the two groups were combined. The use of both qualitative and quantitative data capitalised on the strengths of both techniques. The inclusion of an Anglo-Australian group highlighted key theoretical findings, differences between the two groups and unique contributions made by both samples during the collection of the qualitative data. The use of a pre-test-intervention-post-test design emphasised the reticence of the Italian sample to participate and talk about breast cancer and confirmed and validated the consistency of the responses across the two interviews for both samples. The inclusion of non-cued responses allowed the researcher to identify the key salient issues relevant to the two groups. The limitations of the present research were the lack of many women who were not screening and reliance on self-report responses, although few differences were observed between the Pre- and Post-Test comparisons. The theoretical contribution of the HBM and the TRA variables was minimal in relation to screening mammography or attendance at the CLP. The applicability of these health behaviour theories may be less relevant for women today as they clearly knew the benefits of and the seriousness of breast cancer screening. The present research identified the applicability of the risk variables to the Italian women and the relevance of the locus of control variables to the Anglo-Australian women. Thus, clear cultural differences occurred between the two groups. The inclusion of the illness representations was advantageous as the responses highlighted ideas and personal theories salient to the women not identified by the HBM. The use of the illness representations and the qualitative responses further confirmed the relevance of the risk variables to the Italian women and the locus of control variables to the Anglo-Australian women. Attendance at the CLP did not influence the women to attend for mammography screening. Behavioural changes did not occur between the Pre- and Post-Test interviews. Small incremental changes as defined by the TTM and the stages of change may have occurred. Key practical implications for the CLP were identified. Improving the recruitment methods to gain a higher proportion of women who do not screen is imperative for the CLP promoters. The majority of the Italian and Anglo-Australian women who attended the information sessions were women who screen. The fact that Italian women do not like talking or thinking about cancer presents a challenge to promoters of the CLP. The key theoretical finding that Italian women dread breast cancer but comply with their doctor provides clear strategies to improve attendance at mammography screening. In addition, the inclusion of lay health advisors may be one way of increasing attendance to the CLP by including Italian women already attending screening and likely to have attended a CLP session. The present research identified the key finding that improving Anglo-Australian attendance at an information session is related to debunking the myth surrounding familial risk of breast cancer and encouraging the Anglo-Australian women to take more control of their health. Improving attendance for Italian women is related to reducing the fear and dread of breast cancer and building on the compliance pattern with medical authority. Therefore, providing an information session in the target language is insufficient to attract non-screeners to the session and then to screen for breast cancer. Suggestions for future research in relation to screening mammography were to include variables from more than one theory or model, namely the risk, locus of control and illness representations. The inclusion of non-cued responses to identify salient beliefs is advantageous. In addition, it is imperative to describe the profile of the cultural sample in detail, include detailed descriptions of the translation process and be aware of the tendency of Italian women to acquiesce with medical authority.

Service screening with mammography was implemented in Northern Sweden between 1989 and 1998, covering 190,000 women aged 40-74 years constituting the target population in the area. The aim of this thesis was the evaluation of mammography screening in Northern Sweden with special focus on selected screening performance indicators and on the disease outcome. We analysed interval cancer (IC) incidence and episode sensitivity in the Norrbotten Mammography Screening Programme (NMSP) for the period 1989-2002. An overall IC rate at 1.1/1000 and IC rate ratio at 38% was found and epsiode sensitivity was estimated at 62-73%, in concert with reference values of the European guidelines. Radiological classification of the IC cases in three rounds of the NMSP showed that true, occult, missed and minimal signs IC, were present in 48%, 10%, 14% and 28% of the cases. We analysed early death from breast cancer (n=342) in Northern Sweden during the first five years of mammography service screening. Most fatal cases were advanced and incurable on diagnosis. In a few screen-detected cases with favourable prognostic factors the fatal outcome was unexpected. We estimated breast cancer survival by detection mode in 5120 women with breast cancer. We found a significantly favourable survival among IC cases compared to cases among uninvited. We studied breast cancer mortality in relation to mammography screening. Our findings indicated a long-term reduction of breast cancer mortality by 26-30% among women invited to screening and by 31-35% among women screened compared to not screened. We conclude from our evaluation of the mammography screening in Northern Sweden that women benefited from this public health intervention in form of improved survival and reduced mortality.

Implications of widespread mammography screening remain controversial, and major health organizations in the US adopt different guidelines reflecting significant variations in actual practice. Literature suggests that implementation of routine screening over the past 30 years has incurred less benefit and more harms than is formerly believed.

Aims: In 3 phases, this thesis explores: radiation doses delivered to women during mammography, methods to estimate mean glandular dose (MGD), and the use of mammographic breast density (MBD) in MGD calculations. Firstly, it examines Diagnostic reference levels (DRLs) for digital mammography in Australia, with novel focus on the use of compressed breast thickness (CBT) and detector technologies as a guide when determining patient derived DRLs. Secondly, it analyses the agreement between Organ Dose estimated by different digital mammography units and calculated MGD for clinical data. Thirdly, it explores the novel use of MBD in MGD calculations, suggesting a new dose estimation called the actual glandular dose (AGD), and compares MGD to AGD. Methods: DICOM headers were extracted from 52405 anonymised mammograms using 3rd party software. Exposure and QA information were utilised to calculate MGD using 3 methods. LIBRA software was used to estimate MBD for 31097 mammograms. Median, 75th and 95th percentiles were calculated across MGDs obtained for all included data and according to 9 CBT ranges, average population CBT, and for 3 detector technologies. The significance of the differences, correlations, and agreement between MGDs for different CBT ranges, calculation methods, and different density estimation methods were analysed. Conclusions: This thesis have recommended DRLs for mammography in Australia, it shows that MGD is dependent upon CBT and detector technology, hence DRLs were presented as a table for different CBTs and detectors. The work also shows that Organ Doses reported by vendors vary from that calculated using established methodologies. Data produced also show that the use of MGD calculated using standardised glandularities underestimates dose at lower CBTs compared to AGD by up to 10%, hence, underestimating radiation risk. Finally, AGD was proposed; it considers differences in breast composition for individualised radiation-induced risk assessment.

Background The debate regarding the lower age limit for mammography service screening is old and lively; a product in part of the lower breast cancer risk in younger ages as well as the limited data available for studies of the younger age group. Recently the idea of inviting only high risk groups has gained momentum, however high risk might not be equivalent to greater benefit from screening. Therefore, there is a need for information on effectiveness of screening as it relates to young women and to specific risk groups. To this end, this thesis evaluates mammography screening for the age group – 40 to 49 year old women – in terms of breast cancer mortality reduction in total and in subgroups based on breast cancer risk factors. Overdiagnosis of mammography screening is also evaluated for women 40 to 49 years old. In addition, this thesis presents a statistical method to estimate this effectiveness and to test for differences in effectiveness between subgroups adjusted for non-compliance and contamination. Methods The studies of this thesis are based on data from the Screening of Young Women (SCRY) database. The SCRY database consists of detailed information on diagnosis, death, screening exposure and risk factors for breast cancer cases and population size by year (between 1986 and 2005) and municipality for women in Sweden between 40 and 49 years old. The material was divided into a study group consisting of the counties that invited women in the age group 40-49 years to mammography screening, and a contemporaneous control group consisting of the counties that did not. Effectiveness was estimated in terms of rate ratios for two different exposures (invitation to and participation in screening), and overdiagnosis for subsequent screening was estimated adjusting for lead time bias. Defining a reference period enabled adjustment for possible underlying differences in breast cancer mortality and incidence. A statistical model for adjusting for non-compliance and contamination in randomised controlled trials was further developed to allow for adjustment in cohort studies using a Poisson model with log-linear structure for exposure and background risk. Results During the study period (1986-2005), there were 619 and 1205 breast cancer deaths and 6047 and 7790 breast cancer cases in the study group and the control groups, respectively. For women between 40 and 49 years old, the breast cancer mortality reduction was estimated at 26% [95% CI, 17 to 34%] for invited to screening and 29% [95% CI, 20 to 38%] for attending screening. The RR estimates for the high-risk groups based on the risk factors parity, age at birth of first child, and socio-economic status were equal to or higher than that of the low risk groups. The new statistical method showed that the decrease in effectiveness with parity was not a statistically significant trend. The overdiagnosis from subsequent screening for 40 to 49 year old women was estimated at 1% [95 % CI, -6 to 8 %] (i.e., not statistically significant). Conclusion Subgroup specific effectiveness was also estimated. The relative effectiveness of screening for breast cancer with mammography for women age 40 to 49 years appears to be comparable to that for older women. These findings and the fact that there was no statistically significant overdiagnosis from subsequent screening speak for inviting women 40 to 49 years old to screening. High-risk screening for nulliparous women aged 40 to 49 years, for example, might be an alternative in countries where population-based screening for all women between 40 and 49 years old is not possible. However, the matter of risk factors and the effect of their combinations is complex and risk group screening presents ethical and practical difficulties. The new statistical model is a useful tool for analysing cohorts with exposed and non-exposed populations where non-compliance and contamination is a potential source of bias.

Introducció: S'ha demostrat que el cribratge mamogràfic redueix la mortalitat per càncer de mama. Seguint les recomanacions de la Comissió Europea, els països europeus han establert programes poblacionals de cribratge que ofereixen mamografies biennals a dones d'entre 50 i 69 anys d'edat. No obstant això, el cribratge de càncer de mama no està lliure de controvèrsia ja que existeix un debat en relació a l'equilibri entre la reducció de la mortalitat i els efectes adversos. Per a millorar aquest equilibri, l'evidència científica actual dóna suport al cribratge personalitzat. Els estudis de modelització han demostrat que modificar l'interval de cribratge, la prova de cribratge o el rang d'edat de la població objectiu en funció del risc individual de les dones produeix un major benefici que les estratègies convencionals. Per tant, és necessari ampliar la informació actual sobre els factors de risc d'aquesta malaltia i crear models de predicció del risc individual mitjançant l'anàlisi de grans bases de dades poblacionals. Objectiu: L'objectiu general d'aquesta tesi és aprofundir en l'anàlisi del cribratge poblacional del càncer de mama. En concret, aquesta tesi pretén avaluar diferents factors de risc de càncer de mama per a desenvolupar i validar un model de predicció de risc individual d'aquesta malaltia. Es va analitzar com la densitat mamària afecta als diferents indicadors del cribratge en el context de la mamografia digital. A continuació, es van avaluar les diferències en el risc de càncer de mama en funció de si una lesió benigna de mama es va diagnosticar en un cribratge prevalent o un cribratge incident. També es va analitzar la interacció entre la densitat mamària i les lesions benignes en el risc de desenvolupar càncer de mama. Posteriorment, es va realitzar una revisió sistemàtica per a actualitzar l'evidència existent, dur a terme una valoració crítica i una avaluació del risc de biaix i resumir els resultats dels models de risc individualitzats que s'utilitzen per a estimar el risc de càncer de mama en les dones de la població general. Finalment, es va dissenyar un model de predicció individual del risc de càncer de mama i es va validar internament, a partir d'informació fàcilment accessible en un episodi de cribratge. Conclusions: i) Els diferents indicadors de cribratge es veuen afectats negativament per la densitat mamària, disminuint la sensibilitat i el valor predictiu positiu de la prova a mesura que augmenta la densitat mamària. ii) El risc de càncer de mama conferit per una lesió benigna difereix segons la mena de cribratge (prevalent o incident). Fins on sabem, aquest és el primer estudi que analitza l'impacte del tipus de cribratge en el pronòstic de la lesió benigna. iii) El risc de càncer de mama augmenta de manera independent amb la presència d'una lesió benigna i amb una major densitat mamària i es manté elevat durant més de 15 anys. iv) Els models de predicció són eines prometedores per a implementar polítiques de cribratge basades en el risc individualitzat. No obstant això, és un repte recomanar qualsevol d'ells per a la personalització del cribratge ja que necessiten millorar la seva qualitat i capacitat discriminatòria. v) Es va dissenyar i validar internament un model de predicció de risc capaç d'estimar el risc de càncer de mama a curt i llarg termini utilitzant la informació recollida de manera rutinària en el cribratge mamogràfic. El model inclou edat, antecedents familiars de càncer de mama, antecedents de lesió benigna i patrons mamogràfics previs, que van resultar estar relacionats amb un augment del risc de càncer de mama. El model ha de ser validat externament i actualitzat amb noves variables.
Introducción: Se ha demostrado que el cribado mamográfico reduce la mortalidad por cáncer de mama. Siguiendo las recomendaciones de la Comisión Europea, los países europeos han establecido programas poblacionales de cribado que ofrecen mamografías bienales a mujeres de entre 50 y 69 años de edad. Sin embargo, el cribado de cáncer de mama no está libre de controversia ya que existe un debate en cuanto al equilibrio entre la reducción de la mortalidad y los efectos adversos. Para mejorar este equilibrio, la evidencia científica actual apoya el cribado personalizado. Los estudios de modelización han demostrado que modificar el intervalo de cribado, la prueba de cribado o el rango de edad de la población objetivo en función del riesgo individual de las mujeres produce un mayor beneficio que las estrategias convencionales. Por lo tanto, es necesario ampliar la información actual sobre los factores de riesgo de esta enfermedad y crear modelos de predicción del riesgo individual mediante el análisis de grandes bases de datos poblacionales. Objetivo: El objetivo general de esta tesis es profundizar en el análisis del cribado poblacional del cáncer de mama. En concreto, esta tesis pretende evaluar diferentes factores de riesgo de cáncer de mama para desarrollar y validar un modelo de predicción de riesgo individual de esta enfermedad. Se analizó cómo la densidad mamaria afecta a los distintos indicadores de cribado en el contexto de la mamografía digital. A continuación, se evaluaron las diferencias en el riesgo de cáncer de mama en función de si una lesión benigna de mama se diagnosticó en un cribado prevalente o un cribado incidente. También se analizó la interacción entre la densidad mamaria y las lesiones benignas en el riesgo de cáncer de mama. Posteriormente, se realizó una revisión sistemática para actualizar la evidencia existente, llevar a cabo una valoración crítica y una evaluación del riesgo de sesgo y resumir los resultados de los modelos de riesgo individualizados que se utilizan para estimar el riesgo de cáncer de mama en las mujeres de la población general. Por último, se diseñó un modelo de predicción individual del riesgo de cáncer de mama y se validó internamente, basado en información fácilmente accesible en un episodio de cribado. Conclusiones: i) Los distintos indicadores de cribado se ven afectados negativamente por la densidad mamaria, disminuyendo la sensibilidad y el valor predictivo positivo de la prueba a medida que aumenta la densidad mamaria. ii) El riesgo de cáncer de mama conferido por una lesión benigna difiere según el tipo de cribado (prevalente o incidente). Hasta donde sabemos, este es el primer estudio que analiza el impacto del tipo de cribado en el pronóstico de la lesión benigna. iii) El riesgo de cáncer de mama aumenta de forma independiente con la presencia de una lesión benigna y con una mayor densidad mamaria y se mantiene elevado durante más de 15 años. iv) Los modelos de predicción son herramientas prometedoras para implementar políticas de cribado basadas en el riesgo individualizado. Sin embargo, es un reto recomendar cualquiera de ellos para la personalización del cribado ya que necesitan mejorar su calidad y capacidad discriminatoria. v) Diseñamos y validamos internamente un modelo de predicción de riesgo capaz de estimar el riesgo de cáncer de mama a corto y largo plazo utilizando la información recogida de forma rutinaria en el cribado mamográfico. El modelo incluye edad, antecedentes familiares de cáncer de mama, antecedentes de lesión benigna y patrones mamográficos previos, que resultaron estar relacionados con un aumento del riesgo de cáncer de mama. El modelo debe ser validado externamente y actualizado con nuevas variables.
Background: Mammographic screening has been shown to reduce mortality from breast cancer. Following the recommendations of the European Council, European countries have started population-based screening programs that offer biennial mammograms to women aged between 50 and 69 years. The results of the effectiveness of population-based screening are controversial in terms of the balance between mortality reduction and adverse effects. To improve this balance, current evidence supports personalized screening. Modeling studies have shown that modifying the screening interval, screening modality, or age range of the target population based on women's individual risk yields a greater benefit than conventional standard strategies. Several risk models have been designed to estimate women's individual breast cancer risk based on their personal characteristics. However, most of these models have not been specifically developed to estimate the risk of women targeted for breast cancer screening. There is therefore a need to broaden current information on risk factors for breast cancer and the estimation of individual risk prediction models through the analysis of large population-based databases. Aims: The general objective of the thesis is to deepen the analysis of population-based breast cancer screening. Specifically, the aim of this thesis is to assess different breast cancer risk factors in order to develop and validate an individualized breast cancer risk prediction model. We evaluated how breast density affects screening performance indicators in a digital mammography context. Then, we assessed differences in breast cancer risk across benign breast disease diagnosed at prevalent or incident screens. To our knowledge, this is the first time that such an approach has been used. We also evaluated the interaction between breast density and benign breast disease. Subsequently, we performed a systematic review to update the existing evidence, conduct a critical appraisal and risk of bias assessment and summarize the results of the individualized risk models that are used to estimate the risk of breast cancer in women in the general population. Finally, a breast cancer risk prediction model was designed and internally validated, based on information easily accessible at screening. Conclusions: i) Performance screening measures are negatively affected by breast density, with sensitivity and positive predictive value decreasing as breast density increases. ii) The risk of breast cancer conferred by benign breast disease differed according to type of screen (prevalent or incident). To our knowledge, this is the first study to analyze the impact of screening type on the prognosis of benign breast disease. iii) The risk of breast cancer independently increased with the presence of benign breast disease and with greater breast density and remained elevated for over 15 years. iv) Individualized risk prediction models are promising tools for implementing risk-based screening policies. However, it is a challenge to recommend any of them since they need further improvement in their quality and discriminatory capacity. v) We designed and internally validated a risk prediction model able to estimate short- and long-term breast cancer risk using information routinely reported at screening participation. The model included age, family history of breast cancer, benign breast disease and previous mammographic findings, which were found to be related to an increase in breast cancer risk. The model should be externally validated and updated with new variables.
Universitat Autònoma de Barcelona. Programa de Doctorat en Metodologia de la Recerca Biomèdica i Salut Pública

Aims The aim of this thesis was to establish a novel dose and risk model that could serve to accurately calculate a woman’s mean glandular dose (MGD) across a lifetime of breast screening, anywhere from the ages of 40 to 75 years, using only the information from her first screening visit. It would then use this information to allocate that woman to either a low, medium, or high dose category. Following this, the model could then estimate the risk of radiation-induced breast cancer incidence and mortality for a population of women in the allocated dose category, considering specific screening patterns and frequencies of attendance. Methods The model prototype was initially developed with a large dataset of images from the Cancer Institute New South Wales (CINSW), containing 31,097 images from 7,728 screening visits, each corresponding to a separate woman. This was achieved using the already established dose calculation methods. It was then further developed and established using a combined dataset of Hologic images from the CINSW and Lifepool, which contained a total of 20,232 images from 5,076 visits from 4,154 women. Woman’s breast characteristics, such as their mammographic breast density (MBD) and compressed breast thickness (CBT), were extracted from the images and used to model their change with age. This was done in conjunction with the exposure parameters used within those examinations, which could be used to calculate that woman’s MGD across any age of screening between 40 to 75 years. The model’s outputs were ultimately validated for accuracy using qualitative and quantitative statistical analyses. Results This project has ultimately provided a novel model that women can use to accurately calculate their individualised MGD for any age of screening between 40 to 75 years, discover what dose category they are in based on their personal breast characteristics, and be able to estimate their population-level lifetime risk of radiation-induced breast cancer incidence and mortality. Taking the average woman, where the Radiation Risk In Mammography Screening (RRIMS) model would have allocated her to the medium dose category, assuming she has undergone a lifetime of screening mammography biennially from 50 to 74 years (i.e., 13 total examinations), her calculated total risk of radiation-induced breast cancer incidence and mortality would be 11.76 and 3.55 cases per 100,000 women screened, respectively. That breast cancer incidence rate equates to only about an increased risk of 0.012%, whereas by comparison the average woman’s inherent baseline lifetime risk of being diagnosed with breast cancer in her lifetime (1-in-8) is over 1000 times higher. RRIMS was then investigated for accuracy in a validation study using a dataset of images that was independent from those used to create the model. Qualitative statistical analysis was employed using the Bland-Altman plots which demonstrated a statistically significant bias between the manually calculated vs the model (RRIMS) predicted dose values, where the mean (bias) was -2.02%, with an upper and lower limit of agreement (LoA) of 40.24% and -44.27%, respectively. Quantitative statistical analysis was also employed with a Kendall’s W of 0.83 (p-value <0.001), which indicated a statistically significant and a reasonably good level of agreement between the manually calculated vs RRIMS predicted dose values. Conclusion For the first time, we now have a tool that provides women with a novel approach for accurately calculating the lifetime individualised dose and population-level risk involved with screening mammography that women and healthcare providers can use to enhance their informed consent discussion regarding their attendance and/or frequency at breast screening programs. This tool can also inform health policy makers that are involved with the potential introduction of alternate screening durations and intervals.

Thesis (M.Ph.)--Georgia State University, 2007.
Title from file title page. Russ Toal, committee chair; Rebecca Cowens-Alvarado, Ike Okosun, committee members. Electronic text (119 p. : col. maps) : digital, PDF file. Description based on contents viewed June 4, 2008. Includes bibliographical references (p. 90-96).

The objective of this study was to examine the relationship between psychosocial correlates (big 5 personality traits, dispositional optimism, the Health Belief Model, breast cancer fear, mammography self efficacy, and social support) and breast self examination (BSE) and mammography in breast cancer-free women. In order to measure the social support of the participants, the MOS social support survey was adapted to Turkish culture in the scope of study 1. The sample of the study 1 included 241 participants. The analyses showed that Turkish version of the MOS social support survey had satisfactory psychometric properties. The sample of the study 2 was composed of 230 asymptomatic women for breast cancer. Independent samples t-test results indicated that among the Health Belief Model notions, perceived benefit, barrier, confidence, and health motivation significantly differentiated women who practiced BSE and who did not. However, the HBM notions were not able to differentiate women who had mammography and who did not have. Instead, social support significantly clarified the difference between v women who had mammography and women who did not have. Two hierarchical logistic regression analyses were carried out for BSE and mammography. Big 5 personality traits and dispositional optimism were entered at the first step. The HBM factors and self efficacy were entered at the second step. Breast cancer fear was added at the third step
and for the last step social support measures were added to the equation. For BSE, hierarchical logistic regression yielded no significant predictors but BSE confidence and susceptibility from the HBM. For mammography, the hierarchical logistic analysis resulted that only functional support, which was entered at the fourth step was significant. The strengths and limitations, as well as the implications of the findings, were discussed.

This thesis examines and explores women's mammography screening experiences and the factors influencing women's screening behaviours and choices. The sample consisted of Greek women who were recruited from women's organizations in Athens. 189 women completed a survey questionnaire about their values and beliefs in relation to mammography screening, 33 of whom subsequently underwent an in-depth interview to explore their experiences of mammography screening and their decision-making processes. According to the findings, women's mammography screening behaviour depended to a great extent on the quality and nature of their interactions within their social networks. Thus, the quality of information and meanings derived from these interactions was what determined women's behaviour. Family, close friends and doctors appeared to be important in the formation of women's beliefs, perceptions, emotions (fear of cancer) and behaviour in relation to breast screening. Interestingly, fear of cancer had an opposing effect towards their screening behaviour. A tentative model is presented, which attempts to explain the way these influences affect beliefs, perceptions and mammography screening behaviour, using elements of existing behavioural models. Further exploration of the influential factors and associations identified in this study is required.

Breast cancer (BC) screening could reduce its mortality; however, its access is influenced by societal forces. Our objective is to identify the social determinants associated with mammography screening (MS) in women aged 50 to 59 in Peru. In this cross-sectional analysis of the Peruvian Demographic Health Survey, 2015, MS within the past two years was evaluated through self-report. Prevalence for MS was 21.9% [95% CI: 18.9 to 25.1]. The average age was 54 years (s.d.: 2.5). The higher the socioeconomic status, the higher the prevalence of screening (3.2% vs 41.4% in extreme quintiles, p <.001). In the adjusted models, higher socioeconomic status (PR: 5.81, 95% CI: 2.28 to 14.79), higher education level (PR: 2.03, 95% CI: 1.30 a 3,15) and having health insurance from the Ministry of Health (PR: 2.21, 95% CI: 1.28 to 3.82) and EsSalud (PR: 4.37, 95% CI: 2.67 to 7.15), were positively associated with MS. Social inequalities in screening access exist and might translate into inequalities in cancer morbidity and mortality. The Peruvian government urgently needs to improve screening rates in these vulnerable populations.
Revisión por pares

Introduction: Breast cancer is one of the most common types of cancer among women globally and screening by mammography plays a crucial role in detecting cancer. However, screening target ages may differ between countries. For example, the target group is 50-74 years in Australia and 40+ years in Japan, reflecting differences in age-specific incidence rates (ASIR). Breast cancer risk is related to the volume of mammographic breast density (MBD), which has been found to differ among ethnic groups, hence impacting on national screening policies. The thesis is aimed to investigate whether Japanese women living in Australia (JWA) are best served by the current screening policy of BreastScreen Australia. Methods: The thesis is based on findings from two studies: 1. ASIR in Australia and Japan based on secondary data; 2. The comparison of MBD between Australian women (AW), JWA and Japanese women living in Japan (JWJ). De-identified mammography is categorised independently by three specialist clinicians using the BI-RADS® (5th ed.). Bivariate and multivariate analysis were undertaken using SPSS® Statistics. Results: The results show that Australian ASIR rose sharply from age 40 years and peaked at 65-69 years. While in Japan, the highest incidence occurred at 45-49 years and declined after 50 years. In the second study, more than 65% of AW were found in the low MBD category while the majority of JWJ were in the high MBD category. The ORs demonstrated that JWA were approximately 5 times more likely and JWJ were about 15 times more likely to have high MBD compared to AW. These findings have policy implications in the context of setting breast screening targets. Conclusion: The results indicated two critical implications. Firstly, JW aged 40-49 should be included in the screening target age group. Secondly, supplemental screening should be suggested for JW mainly aged 40-49 years. The findings are also crucial for other ethnic migrant women living in Australia.

Mammographic techniques used for screening programmes need to be of the highest quality; hence, the need of a good phantom to mimic breast response to radiation. The phantom materials must be sensitive to small changes in the mammography system and provide a means of evaluating the absorbed dose to the breast. These materials have to provide the same attenuation properties as the real tissues being simulated, for the radiation modalities being investigated. Cross-linked hydrophilic copolymers have the potential to be good phantom materials for the breast as their elemental compositions are similar to soft tissue. Two types of hydrophilic copolymer materials used in this study were designated as ED1S and ED4C. They were made from a certain proportionate mixture of methyl methacrylate and vinyl pyrrolidone. The physical properties of the materials such as liquid uptake and dimensional changes in hydration and dehydration processes were studied. The equilibrium water content of ED1S and ED4C fully hydrated in water was 55% and 70% respectively. The samples underwent distortion when dehydrated and a volume approximation formula for the dehydrated samples was derived. The linear attenuation coefficient and the mass attenuation coefficient of the hydrophilic copolymer materials at photon energies in the mammographic energy region were determined. Both a single beam transmission method and a photon transmission tomography method were used. The results were compared with XCOM calculated attenuation coefficients of water and average breasts using the elemental composition found in the literature. It was found that the mass attenuation coefficient of dry hydrophilic copolymer samples closely fit the XCOM calculated old-age breast (Breast 3) and samples fully hydrated in water fit the calculated young-age breast (Breast 1). Measurements were also carried out to determine the linear attenuation coefficient of normal and abnormal breast tissues at four photon energies in the mammographic energy region. The values found were in good accord with calculated average breast values. However, more studies need to be done as only three samples were used. The electron density of the hydrophilic copolymer materials was determined by using the Compton scattering technique. The electron density for dry ED1S sample was (3.1 +/- 0.4) x 1023 electrons per cm3 and for dry ED4C was (4.4 +/- 0.4) x 1023 electrons per cm3.

The introduction of screening mammography in Australia has been associated with an increase in the incidence of early-stage breast cancer. Concern is growing about the problems caused when women are diagnosed with breast cancer and undergo treatments that do not benefit them because their cancer would not progress, or would progress, but would not become symptomatic within the remaining lifetime of the patient. This is known as overdiagnosis. Screening mammography aims to decrease breast cancer morbidity and mortality by advancing in time the diagnosis and thereby increasing the chance of successful treatment. But overdiagnosis and the consequent overtreatment can cause serious lifelong harm and are therefore considered the major downsides of breast screening. Mounting evidence of the extent of overdiagnosis has led to the recognition that the benefits and harms of breast screening are finely balanced, and women need to know the magnitude of the trade-offs. The extent of overdiagnosis due to breast screening is contested, with published estimates ranging from 1% to 57%. There is a critical need for research investigating the harm to benefit ratio in Australia and quantification of the effects of screening mammography on the incidence of stage-specific breast cancer and overdiagnosis. Individual women require information about the impact of regularly attending screening mammography on breast cancer mortality and overdiagnosis to make informed decisions. A challenge to estimating this in a randomised controlled trial is nonadherence to the trial protocol. Previous systematic reviews have provided estimates of the effect of receiving an invitation to screening on the risk of dying due to breast cancer. Chapter 2 presents a meta-analysis of the screening mammography trials using a simple adjustment that estimates the probability of a reduction in breast cancer mortality and risk of overdiagnosis due to the effect of receiving screening by regularly participating in a breast screening program. Adjustment for nonadherence increased the size of the size of the effect by up to 50%. The prevented fraction of breast cancer mortality at 13-year follow-up increased from 0.22 to 0.30 with deattenuation. The percentage risk of overdiagnosis during the screening period in women invited to screening increased from 19.0% to 29.7%. From 2013 through 2017, the Australian national breast cancer screening programme gradually invited women aged 70 to 74 years to attend screening, following a policy decision to extend invitations to older women. Yet no formal evaluation of the effects of the change in policy on outcomes for women was undertaken. Building on my meta-analysis, in Chapter 3 I used a Markov model and applied the breast cancer mortality reduction and overdiagnosis estimates reported in Chapter 2 to Australian breast cancer incidence and mortality data to estimate the benefits and harms of the new package of biennial screening from age 50 to 74 compared with the previous programme of screening from age 50 to 69. I found that the extra five years of screening results in approximately seven more overdiagnosed cancers to avert one more breast cancer death. Thus extending screening mammography in Australia to older women results in a less favourable harm to benefit ratio than stopping at age 69. To identify temporal trends in stage-specific breast cancer in Australia, I used an observational study design to analyse data on women who received a diagnosis of breast cancer from 1972 to 2012 as recorded in the New South Wales Cancer Registry (Chapter 4). I explored trends in stage-specific incidence before screening and compared them to periods after screening began. I found that screening was not associated with lower incidence of late-stage breast cancer at diagnosis and incidence for all stages remained higher than prescreening levels. In women aged 50 to 69 years, the incidence of carcinoma in situ, localised and regional breast cancer has more than doubled compared to the prescreening era. The data presented in Chapter 4 indicate that excess detection of breast cancer is a problem in New South Wales. Thus I designed an ecological study to quantify overdiagnosis. I estimated the background trend of increasing incidence using two approaches, the first based on the prescreening trend in women of screening age (50 years and older), and the second based on the contemporary trend in women too young to be screened (40 to 44 years of age). From these trends, I estimated the expected age-standardised incidence of breast cancer, by stage at diagnosis, in the absence of screening, for women aged 50 years and over in the years since the national screening mammography program, BreastScreen, was introduced (1988 to 2012). I then calculated the difference in observed and expected incidence rates to determine the excess incidence of early-stage breast cancer and reduction in the incidence of late-stage disease. I found that screening mammography has resulted in overdiagnosis of early-stage and regional breast cancer. I estimate that around six additional cases of early and regional breast cancer are detected for every distant metastatic breast cancer prevented. Due to the substantial increase in detection of carcinoma in situ of the breast observed in Chapter 4, I explored sub-types and causes of this. Chapter 6 presents a descriptive analysis of temporal trends in the incidence of ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS) in women who received a diagnosis from 1972 to 2012, recorded in the NSW Cancer Registry. Carcinoma in situ as a proportion of all breast cancer increased dramatically, and incidence of DCIS across all ages rose from 0.15 per 100,000 during 1972 to 1983 to 16.81 per 100,000 over 2006 to 2012, with the greatest increase seen among women in the target age group for screening (50 to 69 years). DCIS incidence has not stabilized despite screening being well established for over 20 years, and participation rates in the target age range remaining stable. Our observational estimate of overdiagnosis from Chapter 5 is different to those from meta-analyses of randomised controlled trials of screening mammography and some other observational studies. Thus the final paper in this thesis presents a Cochrane Protocol on Overdiagnosis due to screening mammography for women aged 40 years and older (Chapter 7). We present methodology to identify and evaluate all primary epidemiological studies that have quantified overdiagnosis resulting from screening mammography and provide estimates of its frequency (including randomised and observational studies). An approach to assessing the risk of bias due to lead time is also discussed. Trying to quantify the benefits and harms of screening mammography and present them to women using natural frequencies should better enable informed choice, and is consistent with the international shift towards promoting and supporting shared decision making for screening. This thesis provides valuable new evidence about the trade-offs of screening mammography in Australia. The finding that risk of harm is greater than the chance of benefit is consistent with international studies of breast screening and demonstrates the importance of continuing this work to better quantify overdiagnosis for women, clinicians, and policymakers.

Diagnostic methods to effectively image dense breast tissue (DBT) can pose challenges for breast cancer screening. While conventional mammography is the gold standard for breast cancer screening, this technique has a low sensitivity to DBT and can miss about 78% of cancers in DBT, but magnetic resonance imaging (MRI) has a high sensitivity for imaging DBT, and produces a smaller number of false positives. The purpose of this study was to determine the extent to which conventional mammograms can miss breast cancer in women with DBT and to determine if an adjunct method of imaging DBT might detect breast cancers that are missed by mammography alone. Quantitative data were collected from a sample of 300 randomly selected participants using surveys. SPSS statistical software was used to analyze the data with the factor analysis method. Qualitative data were collected by telephone interviews from 10 women who were patients of a breast cancer center. NVivo software was used to analyze the data with the thematic analysis method. All analyses were guided by theoretical framework of von Bertalanffy's general systems theory, Miller's living systems theory, and the theory of intelligent medical diagnosis. Key results determined that a significant number of women with DBT had breast cancer that was undetected by mammograms; results also showed that women with DBT can benefit from breast cancer screening by adding an adjunct screening method (e.g., MRI). This study may contribute to social change by making the breast cancer screening community aware of the potential benefit of adding MRI as an adjunct to conventional screening so that more breast cancers are detected in the early stages of the disease.

Breast cancer is a widespread public health issue in the United States which affects all women. Although mammography is a proven screening tool, screening rates vary widely. Self-reported health status may play a role in how women perceive their risks for developing breast cancer, which may affect mammography use. The purpose of this cross-sectional survey study was to assess the association between self-reported health status and perceived risk for developing breast cancer, as well as perceived barriers towards mammography screening and use. Social action theory, which holds that social and the psychological factors influence health behaviors, served as the theoretical foundation of the study. A convenience sample of 309 African American, non-Hispanic White, and Hispanic women, aged 30+, was recruited to participate in the study. Linear and logistic regression analyses revealed the model including all variables were significance between self-reported health status, demographic characteristics, and the dependent variables perceived risk of breast cancer, receipt of a mammogram in the last 2 years, and barriers (personal, economic, and health). However, self-reported health status was not a significant individual predictor in any of the analyses, and the null hypotheses for the research questions were not rejected. This study may promote positive social change by providing information on the necessity of interdisciplinary and interrelated educational and intervention approaches to address the challenges of women from diverse populations receiving regular mammograms.

There are increasing efforts to support cisgender women to make an informed decision before participating in biennial screening mammography. I adopted a feminist-relational perspective to explore women’s knowledge about screening and determine how screening mammography is socially constructed by women, healthcare providers, and the media. The findings indicated that opportunities for women to make an informed choice regarding their participation in screening mammography are limited and underscore the need to reconceptualise informed decision-making.

Background: Based on previous research, conventional mammography screening has been found to be ineffective for women at high risk, mainly because high-risk women have high breast density and a fast progression rate of breast cancer. Recently, MRI screening was proposed as an additional complementary screening for high-risk women in Ottawa. The addition of MRI to mammography to screen the high-risk population is worth exploring as it may well address the limitations of mammography, especially since MRI has higher sensitivity. Purpose: The goal of this study is to assess the cost-effectiveness off adding MRI to mammography screening for early detection among women of the high-risk population in Ottawa by using conventional values for the society’s/government’s willingness to pay for one life year gained (US$ 50,000). Methods: A discrete-event simulation model was developed to evaluate the cost-effectiveness of adding MRI screening to mammography for high risk women breast screening in Ottawa. Three risk groups were considered; BRCA1, BRCA2 and other high risk. Based on breast annual incidence, screening features, breast cancer progression among high-risk women, treatment and breast cancer survival rates, the model simulates a hypothetical cohort consisting of 5000 women progressing from age 30 to 100 (or to natural death) and calculates the accumulated life years and costs in order to predict the cost of one life year gained by each screening strategy. Univariate sensitivity analysis was performed on the key parameters to determine the robustness of the simulation outcomes. Paired t-tests were used to determine whether the parameters’ variations are statistically significant or not. Results: In the base-case scenario, the incremental cost-effectiveness ratio (ICER) of mammography compared to both screening was CAN$30,043.48 /life year gained (95%CI ±2524.40) which means the addition of MRI to mammography is a cost-effective intervention according to the commonly used willingness-to-pay threshold of US$50,000 per life-year gained. The findings of the sensitivity analysis indicate that the cost-effectiveness of adding MRI screening is statistically significant for most of the parameter variations, however, the degree of change in the ICER is not hugely impactful as in all cases the ICER remained well below the commonly used willingness-to-pay threshold per life year gained. Conclusion: Study results suggested that the addition of MRI has an important role in improving high risk women screening in terms of increasing life years gained compared to receiving mammography screening only. The results of this study support the recommendations of Cancer Care Ontario and the Ontario Health Technology Advisory Committee guidelines of expanding the Ontario Screening Program to integrate MRI with mammography screening for high risk women aged 30 to 69 years.

Breast cancer is one of the leading causes of death amongst women. According to the World Health Organisation (WHO), a significant increase in the incidence of breast cancer is expected in developing countries (such as Nigeria) by 2030. Mammography screening can significantly reduce the mortality and morbidity resulting from breast cancer. In Nigeria, however, 70% of the breast cancer cases are reported at its later stages, and evidence concludes that the participation level of eligible women in the mammography-screening programme is low. This study is the first to explore the factors affecting women’s attendance in mammography screening in the Lagos state via a qualitative approach. A qualitative descriptive approach is used to explore the views of susceptible women living in Lagos state. Seven focus group discussions (n= 65) and face-to-face interviews with five mammography practitioners in Lagos state were conducted. The study was guided by the theory of care seeking behaviour, and participants were questioned through semi-structured interviews and focus group guides. A conventional content analysis method was used to analyse the information gathered from the participants. Results have shown that lack of awareness among women influences their knowledge of benefits and risks, thus exposing them to several forms of fear and cultural issues (such as, trust in wonder drugs, believe in God, and the culture of non-disclosure of problems) which may directly affect their participation in mammography screenings. In addition, professionalism of mammography staff and government’s role in providing an effective mammography screening service were external factors found to influence women’s attendance. To conclude, the need for targeted education within the society is essential, as the participants identified that education might improve awareness, reduce fear and improve women’s attendance.