High-risk populations as targets for breast cancer prevention trials

Breast cancer risk stratification using genetic and non-genetic risk assessment tools for 246,142 women in the UK Biobank

PURPOSE

The benefit of using individual risk prediction tools to identify high-risk individuals for breast cancer (BC) screening is uncertain, despite the personalized approach of risk-based screening.

METHODS

We studied the overlap of predicted high-risk individuals among 246,142 women enrolled in the UK Biobank. Risk predictors assessed include the Gail model (Gail), BC family history (FH, binary), BC polygenic risk score (PRS), and presence of loss-of-function (LoF) variants in BC predisposition genes. Youden J-index was used to select optimal thresholds for defining high-risk.

RESULTS

In total, 147,399 were considered at high risk for developing BC within the next 2 years by at least 1 of the 4 risk prediction tools examined (Gail2-year > 0.5%: 47%, PRS2-yea r > 0.7%: 30%, FH: 6%, and LoF: 1%); 92,851 (38%) were flagged by only 1 risk predictor. The overlap between individuals flagged as high-risk because of genetic (PRS) and Gail model risk factors was 30%. The best-performing combinatorial model comprises a union of high-risk women identified by PRS, FH, and, LoF (AUC2-year [95% CI]: 62.2 [60.8 to 63.6]). Assigning individual weights to each risk prediction tool increased discriminatory ability.

CONCLUSION

Risk-based BC screening may require a multipronged approach that includes PRS, predisposition genes, FH, and other recognized risk factors.

Optimal breast cancer risk reduction policies tailored to personal risk level

Depending on personal and hereditary factors, each woman has a different risk of developing breast cancer, one of the leading causes of death for women. For women with a high-risk of breast cancer, their risk can be reduced by two main therapeutic approaches: 1) preventive treatments such as hormonal therapies (i.e., tamoxifen, raloxifene, exemestane); or 2) a risk reduction surgery (i.e., mastectomy). Existing national clinical guidelines either fail to incorporate or have limited use of the personal risk of developing breast cancer in their proposed risk reduction strategies. As a result, they do not provide enough resolution on the benefit-risk trade-off of an intervention policy as personal risk changes. In addressing this problem, we develop a discrete-time, finite-horizon Markov decision process (MDP) model with the objective of maximizing the patient's total expected quality-adjusted life years. We find several useful insights some of which contradict the existing national breast cancer risk reduction recommendations. For example, we find that mastectomy is the optimal choice for the border-line high-risk women who are between ages 22 and 38. Additionally, in contrast to the National Comprehensive Cancer Network recommendations, we find that exemestane is a plausible, in fact, the best, option for high-risk postmenopausal women.

Epidemiology, genetics, and risk evaluation of postmenopausal women at risk of breast cancer

Breast cancer risk factors have been studied for the past three decades, and the single most important risk factor is age. Hormonally linked adult reproductive and anthropometric risk factors contribute to the etiology of postmenopausal breast cancer. The risk of breast cancer increases among women older than 50 years of age who have benign breast disease, especially those with atypical ductal or lobular hyperplasia. Lobular carcinoma in situ increases risk significantly, as do a family history of breast cancer in first-degree relatives and the presence of BRCA1 or BRCA2 mutations. Diet, exercise, and environmental factors play a very small role in overall risk. Mammographic breast density increases relative risk fivefold among women with the highest density, and breast cancer risk is two to three times greater in women with elevated serum levels of estradiol or testosterone. Multivariate risk models allow determination of composite relative risks and cumulative lifetime risk, although improved models for African American women are required. For postmenopausal women, newer risk models are being developed and validated that include age, breast density, race, ethnicity, family history of breast cancer, a previous breast biopsy, body mass index, age at onset of natural menopause, hormone therapy, and previous false-positive mammography. A simpler model that includes only age, breast cancer in first-degree relatives, and previous breast biopsy performs well for estrogen receptor-positive breast cancer in postmenopausal women. As many as 10 million women in the United States are at increased risk, and clinicians are obligated to identify these women and manage their risk appropriately.

Prospective screening study of 0.5 Tesla dedicated magnetic resonance imaging for the detection of breast cancer in young, high-risk women

Background

Evidence-based screening guidelines are needed for women under 40 with a family history of breast cancer, a BRCA1 or BRCA2 mutation, or other risk factors. An accurate assessment of breast cancer risk is required to balance the benefits and risks of surveillance, yet published studies have used narrow risk assessment schemata for enrollment. Breast density limits the sensitivity of film-screen mammography but is not thought to pose a limitation to MRI, however the utility of MRI surveillance has not been specifically examined before in women with dense breasts. Also, all MRI surveillance studies yet reported have used high strength magnets that may not be practical for dedicated imaging in many breast centers. Medium strength 0.5 Tesla MRI may provide an alternative economic option for surveillance.

Methods

We conducted a prospective, nonrandomized pilot study of 30 women age 25–49 years with dense breasts evaluating the addition of 0.5 Tesla MRI to conventional screening. All participants had a high quantitative breast cancer risk, defined as ≥ 3.5% over the next 5 years per the Gail or BRCAPRO models, and/or a known BRCA1 or BRCA2 germline mutation.

Results

The average age at enrollment was 41.4 years and the average 5-year risk was 4.8%. Twenty-two subjects had BIRADS category 1 or 2 breast MRIs (negative or probably benign), whereas no category 4 or 5 MRIs (possibly or probably malignant) were observed. Eight subjects had BIRADS 3 results, identifying lesions that were "probably benign", yet prompting further evaluation. One of these subjects was diagnosed with a stage T1aN0M0 invasive ductal carcinoma, and later determined to be a BRCA1 mutation carrier.

Conclusion

Using medium-strength MRI we were able to detect 1 early breast tumor that was mammographically undetectable among 30 young high-risk women with dense breasts. These results support the concept that breast MRI can enhance surveillance for young high-risk women with dense breasts, and further suggest that a medium-strength instrument is sufficient for this application. For the first time, we demonstrate the use of quantitative breast cancer risk assessment via a combination of the Gail and BRCAPRO models for enrollment in a screening trial.

[Application of the Gail method of calculating risk in the population of Valencia]

BACKGROUND

The objective of this study was to verify whether the method defined by Gail is applicable and predictive in a population of women in Valencia (Spain).

POPULATION AND METHODS

Of the 685 patients diagnosed with breast cancer and attended-to in 2000-2001, 186 incident cases were identified. The variables studied were obtained from a specific questionnaire which included characteristics of reproductive history, number of biopsies and contraceptive pill consumption prior to the diagnosis. Using the model of the National Surgical Adjuvant Breast and Bowel Project (NSABP), an adaptation of the Gail model, the risk of developing breast cancer at 5 years was estimated.

RESULTS

Only 40% of those women diagnosed as having breast cancer would have been identified as a high-risk patient by the Gail method. With our population group, the method detected the elderly women with a medical history of breast cancer who developed advanced stage disease.

CONCLUSIONS

The Gail method does not adapt well to the study population of Valencia. It would be necessary to add other risk-factors to the Gail method so as to identify more patients in our area.

Current comprehensive assessment and management of women at increased risk for breast cancer

The potential for reducing the risk of breast cancer through selective estrogen receptor modulators, aromatase inhibitors, and surgery has generated interest in the use of quantitative models of risk assessment. With the addition of ductal lavage cytology to traditional epidemiologic risk factors, a discovery of cellular atypia can result in refinement of assigned risk values, while simultaneously optimizing patient selection for selective estrogen receptor modulators utilization. In view of increasing complexity in this arena, a Risk Assessment Working Group was formed to outline management strategies for the patient at an elevated risk for the development of breast cancer. No longer a statistical exercise, quantitative risk assessment is part of basic breast care and comprehensive management includes a discussion of the following: ductal lavage for improved risk stratification, multiple options for risk reduction, and high risk surveillance strategies that might incorporate investigational imaging protocols.

Management of the high-risk patient

Comprehensive breast cancer risk management is a practical tool that can now be regarded as a necessary clinical component of women's health. Risk assessment is the starting point for counseling women about risk, and it facilitates rational decision-making about prophylactic surgery, initiation of screening at an early age, and initiating preventive interventions. The availability of risk assessment models permit rapid risk calculation during routine clinical encounters, and risk profiles can be easily updated at subsequent clinical visits. Clinicians can now incorporate risk assessment and management into their routine screening and health maintenance appointments. Additional prospective clinical trials should be conducted to define the optimal use of existing management strategies, develop refined risk assessment instruments that incorporate additional risk-factor information, and evaluate populations for whom validated risk-assessment approaches do not yet exist.

Ductal lavage: clinical utility and future promise

This article discusses the use of ductal lavage to enhance the tolerability, efficiency, and reproducibility of collecting breast duct epithelial cells for analysis for breast cancer risk assessment. Aspects discussed include the rationale for use of ductal lavage, identification of appropriate candidates for the procedure, clinical implications, ongoing evaluation of the procedure, and its future utility.

Reports of information and support needs of daughters and sisters of women with breast cancer

The aim of this study was to describe the information and support needs of women who have primary relatives with breast cancer. The Information and Support Needs Questionnaire (ISNQ) was developed and revised from previous qualitative and pilot studies. The ISNQ addressed concepts of the importance of, and the degree to which, 29 information and support needs related to breast cancer had been met. The study sample consisted of 261 community-residing women who had mothers, sisters, or a mother and sister(s) with breast cancer. Data were collected using a mailed survey. In addition to the ISNQ, additional items addressed family and health history, breast self-care practices, perception of the impact of the relative's breast cancer and other variables. Also included were established and well-validated measures of anxiety and depression. The findings document women's priority information and support needs. The information need most frequently identified as very important was information about personal risk of breast cancer. Other highly rated needs addressed risk factors for breast cancer and early detection measures. Generally, the women perceived that their information and support needs were not well met. These findings illuminate needs of women for more information and support when they have close family relatives with breast cancer and opportunities for primary care providers to assist women in addressing their needs.

Evaluation of potential confounders in planning a study of occupational magnetic field exposure and female breast cancer

We examined potential confounding factors that, if unaccounted for, could possibly produce a spurious association in a study of breast cancer among women occupationally exposed to magnetic fields. For each risk factor, we estimated strength of association, prevalence in the general population, and prevalence of the risk factor in the exposed group required to explain completely hypothetical odds ratios between occupational exposure to magnetic fields and breast cancer. We performed similar analyses for two, three, four, and five confounding factors acting simultaneously. Factors numerically capable of substantial confounding included obesity, continent of birth, family history of breast cancer in a first-degree relative, densities on the mammogram, benign proliferative breast disease, history of cancer in one breast, and consumption of at least two alcoholic drinks per day. Nevertheless, only continent of birth, history of cancer, obesity, and consumption of alcohol could potentially be related to occupation. Uncontrolled confounders, either alone or in combination, could possibly account for odds ratios in the 1.2-1.3 range but were very unlikely to produce an odds ratio of more than 1.5. A spurious negative association between magnetic fields and breast cancer could occur if the exposed group included a large number of immigrants from Asia and Africa.

Information and support needs of women with primary relatives with breast cancer: development of the Information and Support Needs Questionnaire

AIMS OF THE STUDY

The aim was to develop and pilot test a newly developed measure, The Information and Support Needs Questionnaire (ISNQ), for use with women with primary relatives with breast cancer.

BACKGROUND/RATIONALE

Breast cancer is a major risk to the health of women in the United Kingdom (UK). Increasingly, research is documenting women's needs for information and support, particularly at the time of diagnosis. However, to date there is little understanding of the information and support needs of women who have a family history of breast cancer. Contributing to the dearth of understanding of female relatives' needs is the lack of valid and reliable instruments for use in descriptive and intervention research with this population.

DESIGN/METHODS

The ISNQ and survey items documenting family history, sources of information and support for breast cancer risk, breast self-care practices, and other variables were pilot tested for the acceptability of the measures, appropriateness of the data collection methods, initial psychometric properties of the ISNQ, and time and financial costs of administration. Data were collected from 39 women living in the North-west of England who had primary relatives with breast cancer using mailed questionnaires and follow-up telephone interviews.

FINDINGS

The items on the ISNQ were reported to be clear, acceptable to women and to yield relevant data. The psychometric properties of the new measure were satisfactory with a high reliability coefficient alpha. Descriptive findings indicate that women had moderate to high needs for information and support, but reported that these needs were not well met.

CONCLUSIONS

The results of this pilot are guiding the development of a larger study in which the information and support needs of women with a family history of breast cancer are explored.

Screening for breast and cervical cancers: the importance of knowledge and perceived cancer survivability

INTRODUCTION

This study examines the association between recent screening for breast and cervical cancers, knowledge of cancer risk factors, and perceptions of surviving cancer.

METHODS

Data were from the Cancer Control Supplement to the 1992 National Health Interview Survey (NHIS-CCS). The dependent variable combined breast and cervical cancer screening practices into a single composite index. Two independent variables combined women's knowledge about breast and cervical cancers into single indicators--one representing risk factor knowledge, the other representing perceived likelihood of surviving breast and cervical cancers following early detection.

RESULTS

Multivariate analysis showed that recency of screening for both breast and cervical cancers was associated with knowledge of cancer risk factors and perceptions of surviving cancer. Education, household income, and smoking status also were correlates of comprehensive screening. Significant interactions between income and perceived survivability, and between education and perceived survivability suggested that the effects of income and education on comprehensive screening varied with perceptions about surviving cancer.

CONCLUSION

The study suggests that knowledge and attitudinal questions can be combined for two diseases to enhance understanding of who is most likely to be screened comprehensively for breast and cervical cancers. Although national trends show that large percentages of women over age 50 are having mammograms and Pap tests, this progress is not likely to be sustained unless existing barriers are eliminated. Limited knowledge about breast and cervical cancer risk factors and misperceptions about survival from cancer represent two of these barriers.

A breast density index for digital mammograms based on radiologists' ranking

The purpose of this study was to develop and evaluate a computerized method of calculating a breast density index (BDI) from digitized mammograms that was designed specifically to model radiologists' perception of breast density. A set of 153 pairs of digitized mammograms (cranio-caudal, CC, and mediolateral oblique, MLO, views) were acquired and preprocessed to reduce detector biases. The sets of mammograms were ordered on an ordinal scale (a scale based only on relative rank-ordering) by two radiologists, and a cardinal (an absolute numerical score) BDI value was calculated from the ordinal ranks. The images were also assigned cardinal BDI values by the radiologists in a subsequent session. Six mathematical features (including fractal dimension and others) were calculated from the digital mammograms, and were used in conjunction with single value decomposition and multiple linear regression to calculate a computerized BDI. The linear correlation coefficient between different ordinal ranking sessions were as follows: intraradiologist intraprojection (CC/CC): r = 0.978; intraradiologist interprojection (CC/MLO): r = 0.960; and interradiologist intraprojection (CC/CC): r = 0.968. A separate breast density index was derived from three separate ordinal rankings by one radiologist (two with CC views, one with the MLO view). The computer derived BDI had a correlation coefficient (r) of 0.907 with the radiologists' ordinal BDI. A comparison between radiologists using a cardinal scoring system (which is closest to how radiologists actually evaluate breast density) showed r = 0.914. A breast density index calculated by a computer but modeled after radiologist perception of breast density may be valuable in objectively measuring breast density. Such a metric may prove valuable in numerous areas, including breast cancer risk assessment and in evaluating screening techniques specifically designed to improve imaging of the dense breast.

Psychological issues in cancer genetics: current research and future priorities

There has been a rapid expansion of genetics research in the field of cancer since cancer predisposing genes are now known to cause a proportion of common cancers as well as rarer cancer syndromes. As a result, the psychosocial impact of being at high risk of cancer has become a focus of evaluation, and studies are being reported which set out to evaluate both the uptake and psychological outcome of genetic counselling, testing and surveillance. Available data concerning psychological aspects are reviewed, including for example, possible implications of genetic testing, attitudes and uptake of breast screening and accuracy of women's risk estimates. Work is in progress to assess the more controversial areas of prophylactic mastectomy, and chemoprevention. Other research examines the longer term impact of belonging to a Cancer Family, and of interventions offered to high risk families. This is crucial since the uptake of counselling and testing is likely to be much greater in cancer prone families than those with other genetic disorders, yet detection and prevention strategies are still unevaluated for important genetically determined cancers such as breast cancer.

Assessing individual risk for breast cancer: risky business

There is increasing demand for prediction of individual women's risk for breast cancer from women, clinicians, researchers, and health planners. Risk assessment for breast cancer is the process of identifying characteristics of an individual woman that are relevant to her risk, and combining those characteristics into a quantitative or qualitative risk profile. This article reviews and compares available methods of predicting risk, discusses benefits and drawbacks to the methods, and compares risk estimates for several hypothetical subjects using the different methods. Current and future uses for risk assessment are described. Risk assessment, while a promising tool for research now, and for clinical areas in the future, is still too imprecise for accurate prediction of breast cancer occurrence in individuals.

Adherence and psychological adjustment among women at high risk for breast cancer

Increasingly, women with a positive family history of breast cancer are being targeted for cancer prevention and control efforts. Two findings have been demonstrated consistently across studies of this high risk population. First, these women often have high levels of psychological distress, as well as persistent and intrusive worries about developing breast cancer. Second, despite their increased risk for developing breast cancer, a substantial proportion of these women do not adhere to recommended breast cancer screening guidelines. There is growing evidence that psychological distress is an important barrier to adherence among high risk women. Despite this, little is known about how to intervene to improve psychological adjustment and adherence in this population. In the present paper, we review the literature on adherence and psychological adjustment in women who are at increased risk for breast cancer because of a positive family history of disease. This review provides the basis for a discussion of potential intervention strategies designed to increase adherence and reduce psychological distress in this population. Finally, we present some of the psychological implications of recent developments in genetic testing for breast cancer susceptibility.

Clinical management of women at increased risk for breast cancer

A large number of women in the population are at risk for the development of breast cancer. Methods now exist to accurately assess risk and to provide quantitative estimates of the chance of a woman developing breast cancer in her lifetime. Histologic assessment of premalignant breast pathology aids in the evaluation of risk. The availability of primary chemoprevention clinical trials reduces the number of indications for prophylactic mastectomy. Women at risk for breast cancer and women who have had a malignant lesion at another anatomic site have an increased risk for new cancers at multiple sites. We propose screening strategies based on epidemiologic information about the risks of these diseases and on the predictive value of the available screening tests. The merits and inadequacies of specific management strategies are considered. We review the risks and benefits of estrogen replacement therapy for women at increased risk for breast cancer and consider the ethical implications of both risk assessment and the various interventions.