Evaluation of established breast cancer risk factors as modifiers of BRCA1 or BRCA2: a multi-center case-only analysis

Risk Factors for Ovarian Cancer by BRCA Status: A Collaborative Case-Only Analysis

BACKGROUND

Women with an inherited pathogenic variant in BRCA1 or BRCA2 have a greatly increased risk of developing ovarian cancer, but the importance of behavioral factors is less clear. We used a case-only design to compare the magnitude of associations with established reproductive, hormonal, and lifestyle risk factors between BRCA mutation carriers and noncarriers.

METHODS

We pooled data from five studies from the Ovarian Cancer Association Consortium including 637 BRCA carriers and 4,289 noncarriers. Covariate-adjusted generalized linear mixed models were used to estimate interaction risk ratios (IRR) and 95% confidence intervals (CI), with BRCA (carrier vs. noncarrier) as the response variable.

RESULTS

IRRs were above 1.0 for known protective factors including ever being pregnant (IRR = 1.29, 95% CI; 1.00-1.67) and ever using the oral contraceptive pill (1.30, 95% CI; 1.07-1.60), suggesting the protective effects of these factors may be reduced in carriers compared with noncarriers. Conversely, the IRRs for risk factors including endometriosis and menopausal hormone therapy were below 1.0, suggesting weaker positive associations among BRCA carriers. In contrast, associations with lifestyle factors including smoking, physical inactivity, body mass index, and aspirin use did not appear to differ by BRCA status.

CONCLUSIONS

Our results suggest that associations with hormonal and reproductive factors are generally weaker for those with a pathogenic BRCA variant than those without, while associations with modifiable lifestyle factors are similar for carriers and noncarriers.

IMPACT

Advice to maintain a healthy weight, be physically active, and refrain from smoking will therefore benefit BRCA carriers as well as noncarriers.

Characterization of the HER2 status in BRCA-mutated breast cancer: a single institutional series and systematic review with pooled analysis

BACKGROUND

Pathogenic variants (PVs) in BRCA1/2 genes account for ∼6% of breast and 20% of ovarian cancers. Most breast tumors developed by BRCA1 carriers are triple negative. BRCA2 tumors have similar rates of estrogen receptor positivity as sporadic controls but are less likely to be human epidermal growth factor receptor 2 (HER2)-positive. Prevalence of HER2 positivity among breast cancers (BCs) in BRCA1/2 mutation carriers is poorly and variably described, ranging from 0% to 10% and 0% to 13% in BRCA1 and BRCA2 carriers, respectively.

PATIENTS AND METHODS

We assessed the prevalence of HER2 positivity among a single institutional cohort of 398 BCs developed in carriers of BRCA1/2 PVs (240 BRCA1, 158 BRCA2). Subsequently, a systematic review of the literature and pooled analysis was carried out.

RESULTS

In our series we found a 7% HER2 positivity rate among all first BRCA1/2 BCs overall. In BRCA1 carriers, 5.4% of BCs were HER2-positive compared with 9.5% in BRCA2-mutated patients. Among bilateral BCs, HER2-positive cases were 15.2% in the BRCA1 group and 23.1% in the BRCA2 group. Notably, six BRCA1 and eight BRCA2 carriers showed discordant HER2 status between BC and bilateral BC (23.7%, 14/59). The systematic review included 21 083 BRCA1/2 patients from 73 eligible studies. The pooled rate of BRCAmut/HER2-positive BCs is 9.1% (95% confidence interval 7.3% to 11.2%). BRCA1 and BRCA2 when reported as separate data ranged from 0% to 33.3% (mean 8.3%) and from 0% to 86% (mean 10.3%), respectively.

CONCLUSIONS

As compared with sporadic cases, BCs occurring in BRCA1 and/or BRCA2 PVs carriers are less frequently HER2-positive. Prevalence of HER2 positivity in our series was consistent with pooled analysis and did not exceed 10%. Although not common, co-existence of BRCA mutations and HER2 overexpression and/or gene amplification should be acknowledged. More research is needed to better characterize this subgroup of patients who should not be excluded a priori from clinical trials of targeted therapy for BRCA1/2-driven cancers.

Lifestyle, Behavioral, and Dietary Risk Factors in Relation to Mammographic Breast Density in Women at High Risk for Breast Cancer

BACKGROUND

Women at high risk for breast cancer due to genetics or risk factor profiles are counseled to adopt lifestyle, behavioral, and dietary changes to help reduce their risk. These recommendations are based on studies of women at average risk, so their effectiveness in high-risk women is unclear.

METHODS

We evaluated the impact of physical activity, smoking, alcohol consumption, and intake of folate and carotenoids on mammographic breast density-a proxy for breast cancer risk-among 387 high-risk women. Exposures were self-reported on questionnaires. Breast dense area, nondense area, and percent dense area were measured from screening mammograms with Library for Breast Radiodensity Assessment software. Cross-sectional associations were estimated with multivariable quantile regression models.

RESULTS

After adjusting for age, adiposity, reproductive history, and use of postmenopausal hormones, no breast density measure was associated with physical activity level, smoking status, alcohol consumption, or estimated intake of folate, alpha-carotene, beta-carotene, lutein/zeaxanthin, and beta-cryptoxanthin. Lycopene intake was associated with lower dense area when comparing the highest and lowest intake categories (adjusted difference in median = -14 cm², 95% confidence interval: -29 to 1.3 cm²). This association may be explained by incomplete adjustment for adiposity.

CONCLUSIONS

Recommended lifestyle, behavioral, and dietary changes to mitigate personal risk of breast cancer do not substantially impact mammographic breast density measures.

IMPACT

Alternative strategies, such as increased uptake of chemoprevention, may better serve risk reduction efforts in women at high risk for breast cancer.

Diet, weight management, physical activity and Ovarian & Breast Cancer Risk in women with BRCA1/2 pathogenic Germline gene variants: systematic review

INTRODUCTION

Women with pathogenic germline gene variants in BRCA1 and/or BRCA2 are at increased risk of developing ovarian and breast cancer. While surgical and pharmacological approaches are effective for risk-reduction, it is unknown whether lifestyle approaches such as healthful dietary habits, weight management, and physical activity may also contribute to risk-reduction. We conducted a systematic review of evidence related to dietary habits, weight status/change, and physical activity on ovarian and breast cancer risk among women with BRCA1/2 pathogenic variants.

METHODS

We searched Medline, EMBASE, CENTRAL, PubMed, and clinicaltrials.gov up to October 3, 2019. We identified 2775 records and included 21.

RESULTS

There is limited evidence related to these factors and ovarian cancer risk. For breast cancer risk, evidence suggests higher diet quality, adulthood weight-loss of ≥10 pounds, and activity during adolescence and young-adulthood may be linked with decreased risk. Higher meat intake and higher daily energy intake may be linked with increased risk.

CONCLUSIONS

There is not enough evidence to suggest tailored recommendations for dietary habits or weight management among women with BRCA1/2 pathogenic variants compared to the general population for ovarian and breast cancer risk-reduction, and physical activity recommendations should remain the same.

Alcohol Consumption, Cigarette Smoking, and Risk of Breast Cancer for BRCA1 and BRCA2 Mutation Carriers: Results from The BRCA1 and BRCA2 Cohort Consortium

BACKGROUND

Tobacco smoking and alcohol consumption have been intensively studied in the general population to assess their effects on the risk of breast cancer, but very few studies have examined these effects in BRCA1 and BRCA2 mutation carriers. Given the high breast cancer risk for mutation carriers and the importance of BRCA1 and BRCA2 in DNA repair, better evidence on the associations of these lifestyle factors with breast cancer risk is essential.

METHODS

Using a large international pooled cohort of BRCA1 and BRCA2 mutation carriers, we conducted retrospective (5,707 BRCA1 mutation carriers and 3,525 BRCA2 mutation carriers) and prospective (2,276 BRCA1 mutation carriers and 1,610 BRCA2 mutation carriers) analyses of alcohol and tobacco consumption using Cox proportional hazards models.

RESULTS

For both BRCA1 and BRCA2 mutation carriers, none of the smoking-related variables was associated with breast cancer risk, except smoking for more than 5 years before a first full-term pregnancy (FFTP) when compared with parous women who never smoked. For BRCA1 mutation carriers, the HR from retrospective analysis (HRR) was 1.19 [95% confidence interval (CI), 1.02-1.39] and the HR from prospective analysis (HRP) was 1.36 (95% CI, 0.99-1.87). For BRCA2 mutation carriers, smoking for more than 5 years before an FFTP showed an association of a similar magnitude, but the confidence limits were wider (HRR = 1.25; 95% CI, 1.01-1.55 and HRP = 1.30; 95% CI, 0.83-2.01). For both carrier groups, alcohol consumption was not associated with breast cancer risk.

CONCLUSIONS

The finding that smoking during the prereproductive years increases breast cancer risk for mutation carriers warrants further investigation.

IMPACT

This is the largest prospective study of BRCA mutation carriers to assess these important risk factors.

Association between meat consumption and risk of breast cancer: Findings from the Sister Study

Meat consumption has been postulated to increase the risk of breast cancer, but this association has not been consistently seen. We examined the association between consumption of different types of meat, meat mutagens and incident invasive breast cancer. Information on consumption of different meat categories and meat cooking practice behaviors was obtained from 42,012 Sister Study participants who completed a Block 1998 Food Frequency Questionnaire at enrollment (2003-2009) and satisfied eligibility criteria. Exposure to meat type and meat mutagens was calculated, and associations with invasive breast cancer risk were estimated using multivariable Cox proportional hazards regression. During follow-up (mean, 7.6 years), 1,536 invasive breast cancers were diagnosed at least 1 year after enrollment. Increasing consumption of red meat was associated with increased risk of invasive breast cancer (HR_{highest vs. lowest quartile} :1.23, 95% CI: 1.02-1.48, p_trend = 0.01). Conversely, increasing consumption of poultry was associated with decreased invasive breast cancer risk (HR _{highest vs. lowest quartile} : 0.85; 95% CI: 0.72-1.00; p_trend = 0.03). In a substitution model with combined red meat and poultry consumption held constant, substituting poultry for red meat was associated with decreased invasive breast cancer risk (HR _{highest vs. lowest quartile} of poultry consumption: 0.72, 95% CI: 0.58-0.89). No associations were observed for cooking practices, estimated heterocyclic amines or heme iron from red meat consumption with breast cancer risk. Red meat consumption may increase the risk of invasive breast cancer, whereas poultry consumption may be associated with reduced risk. Substituting poultry for red meat could reduce breast cancer risk.

BRCA Mutations and Breast Cancer Prevention

Women who inherit a deleterious BRCA1 or BRCA2 mutation face substantially increased risks of developing breast cancer, which is estimated at 70%. Although annual screening with magnetic resonance imaging (MRI) and mammography promotes the earlier detection of the disease, the gold standard for the primary prevention of breast cancer remains bilateral mastectomy. In the current paper, I review the evidence regarding the management of healthy BRCA mutation carriers, including key risk factors and protective factors, and also discuss potential chemoprevention options. I also provide an overview of the key findings from the literature published to date, with a focus on data from studies that are well-powered, and preferably prospective in nature.

Reducing the Risk of Gynecologic Cancer in Hereditary Breast Ovarian Cancer Syndrome Mutation Carriers: Moral Dilemmas and the Principle of Double Effect

Hereditary breast ovarian cancer (HBOC) syndrome is an autosomal dominant disease linked to mutations in the BRCA1 and BRCA2 genes in 90 percent of affected families. Female mutation carriers are highly susceptible to aggressive, often disseminated, usually fatal pelvic-abdominal carcinomatosis. This cancer risk can be markedly reduced by surgical removal of the internal gynecologic organs before the end of the fourth decade of life and by using estrogen-progestin formulations marketed for many years as combined oral contraceptives (COCs). Both risk-reducing methods are associated with unfavorable effects. Relying on the principle of double effect, this essay argues for the ethical justification of prophylactic surgery and the use of COC to reduce the risk of gynecologic cancer in HBOC syndrome mutation carriers. Summary: Hereditary breast ovarian cancer syndrome is an autosomal dominant disease linked to mutations in the BRCA1 and BRCA2 genes in most affected families. Female mutation carriers are highly susceptible to aggressive, often disseminated, usually fatal pelvic-abdominal carcinomatosis. This cancer risk can be markedly reduced by surgical removal of the internal gynecologic organs before the end of the fourth decade of life and by using estrogen-progestin formulations marketed for many years as combined oral contraceptives. Both risk-reducing methods are associated with unfavorable effects. Relying on the principle of double effect, this essay argues for the ethical justification for those unfavorable effects.

Exposure to phthalates in patients with diabetes and its association with oxidative stress, adiponectin, and inflammatory cytokines

Epidemiologic studies have revealed higher concentrations of the metabolites of phthalic acid esters (mPAEs) in patients with type 2 diabetes. On the other hand, oxidative stress, adiponectin, and inflammatory cytokines play important roles in the pathogenesis of diabetes and its complications. However, little information is known about the association between exposure to PAEs and these physiological parameters. Hence, paired urine and blood samples were collected from a total of 329 volunteers, and 11 main mPAEs and malondialdehyde (MDA), as a biomarker of oxidative stress, were measured in the urine samples. Serum adiponectin and tumor necrosis factor-α (TNF-α), a biomarker of inflammation, were also measured. Multivariable linear regression was used to assess the association between urinary mPAEs and these physiological parameters in the total subjects and subjects stratified by age, sex, and body mass index (BMI) to elucidate their possible interactions. All 11 mPAEs were detected in the urine with detection rates of 42.9%-100% and geometric means of 0.30-54.52ng/mL (0.44-79.93μg/g creatinine). The mPAEs were all positively associated with MDA levels. There were significant positive associations between monomethyl phthalate (mMP) and TNF-α, and inverse associations between mMP and adiponectin levels. In the stratified analysis, there were age-, sex-, and BMI-specific differences for these associations. The positive associations between mPAEs and MDA were insignificant in some subgroups, especially in the larger age group. However, in the larger BMI group, summed metabolites of di-(2-ethylhexyl) phthalate (∑DEHP) and mono(2-ethylhexyl) phthalate were positively associated with TNF-α, and the concentrations of ∑DEHP were negatively associated with adiponectin. Our findings suggested that PAE exposure is associated with oxidative stress, adiponectin, and inflammatory cytokines in diabetic patients; further studies on toxicology and a comparison with general population are needed.

Reproductive factors as risk modifiers of breast cancer in BRCA mutation carriers and high-risk non-carriers

This study was conducted to identify the role of reproductive factors as environmental modifiers for breast cancer (BC) risk in clinic-based, East-Asian BRCA1 and BRCA2 mutation carriers and non-carriers with high-risk criteria of BRCA mutations (family history (FH) of BC, early-onset BC (aged ≤40 years)). A total of 581 women who were BRCA carriers (222 BRCA1 and 359 BRCA2), 1,083 non-carriers with FH, and 886 non-carriers with early-onset BC were enrolled and interviewed to examine the reproductive factors, from 2007 to 2014. The hazard ratio (HR) and its 95% confidence interval (CI) in the weighted Cox regression model were used to calculate the BC risk based on the reproductive factors. Earlier menarche increased BC risk by 3.49-fold in BRCA2 mutation carriers (95%CI=2.03-6.00) and 3.30-fold in non-carriers with FH (95%CI=1.73-6.34), but was insignificantly associated with BRCA1 carriers and non-carriers for early-onset BC (P-heterogeneity=0.047). Higher parity decreased BC risk in BRCA carriers and non-carriers with FH, especially in BRCA1 carriers (HR=0.27, 95% CI=0.09-0.83 for two parity; and HR=0.23, 95%CI=0.05-1.00 for ≥3 parity), but increased the early-onset BC risk (HR=4.63, 95%CI=2.56-8.51 for >3 parity, p-heterogeneity=0.045). Oral contraceptive (OC) use and longer estrogen exposure periods (≥30 years) were associated with an increased risk of early-onset BC (HR=3.99, 95%CI=1.65-9.67; HR=7.69, 95%CI=1.96-25.01), while OC use was not associated with BC risk in other groups and longer estrogen exposure had rather decreased risk for BC risk (both p-heterogeneity<0.001). Several reproductive factors as risk modifiers could heterogeneously be associated with BC among BRCA1/2 mutation carriers, non-carriers with FH, and early-onset BC non-carriers.

Earlier age at menarche in girls with rapid early life growth: cohort and within sibling analyses

PURPOSE

The purpose of the article was to examine the association of early life growth with age at menarche.

METHODS

Using data from a prospective birth cohort (n = 1134 women, 290 sibling sets), we assessed the association between postnatal growth at 4 months, 1 year, and 4 years and age at menarche, using generalized estimating equations and generalized linear random effects models.

RESULTS

Overall, 18% of the cohort experienced early menarche (<12 years). After accounting for postnatal growth in length, faster postnatal change in weight (per 10-percentile increase) in all three periods was associated with an increase (range 9%-20%) in the likelihood of having an early menarche. In adjusted linear models, faster weight gains in infancy and childhood were associated with an average age at menarche that was 1.1-1.3 months earlier compared with stable growth. The overall results were consistent for percentile and conditional growth models. Girls who experienced rapid growth (defined as increasing across two major Centers for Disease Control and Prevention growth percentiles) in early infancy had an average age at menarche that was 4.6 months earlier than girls whose growth was stable.

CONCLUSIONS

Faster postnatal weight gains in infancy and early childhood before the age of 4 years are associated with earlier age at menarche.

Large genomic rearrangements in the familial breast and ovarian cancer gene BRCA1 are associated with an increased frequency of high risk features

Large genomic rearrangements (LGRs) account for at least 10% of the mutations in BRCA1 and 5% of BRCA2 mutations in outbred hereditary breast and ovarian cancer (HBOC) families. Data from some series suggest LGRs represent particularly penetrant mutations. 1,034 index cases from HBOC families underwent comprehensive BRCA1 and BRCA2 mutation testing, including screening for LGRs. The personal and family history of 254 identified mutation carriers were compared based on mutation type. Thirty-six LGRs were detected; 32/122 (26%) BRCA1 and 4/132 (3%) BRCA2 mutations. High risk features (bilateral breast cancer, diagnosis <40 years, ovarian cancer, male breast cancer) were more commonly associated with an LGR than a non-LGR mutation (p = 0.008), In families with a BRCA1 LGR the mean age of breast cancer diagnosis was younger than in families with a non-LGR BRCA1 mutation (42.5 vs. 46.1 years, p = 0.007). Across the entire group of mutation positive families the number of relatives affected by breast or ovarian cancer was increased [LGR 3.7 vs. non- LGR 2.8 per family, p value (adjusted for genotype) = 0.047]. Excluding index cases, the odds ratio for breast cancer in BRCA1 families with an LGR was 1.42 (95% CI 1.24-1.63) and for ovarian cancer 1.66 (95% CI 1.10-2.49). The increased cancer risk was reflected in significantly higher risk assessments by mutation prediction tools. LGRs are associated with higher cancer risks. If validated, LGRs could be included in cancer risk prediction tools to improve personalised cancer risk prediction estimates and may guide cost-minimising mutation screening strategies in some healthcare settings.

Prospective evaluation of alcohol consumption and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

Given the adverse effect of alcohol in the development of breast cancer among women in the general population, we evaluated whether a similar association exists among women with a BRCA1 or BRCA2 mutation. Information regarding baseline daily alcohol consumption was abstracted from a research questionnaire for 3067 BRCA mutation carriers enrolled in a prospective cohort study. Women were followed biennially until the date of the last follow-up questionnaire, date of breast cancer diagnosis, date of prophylactic bilateral mastectomy, or date of death. Cox proportional hazards models were used to estimate relative risks (RRs) and 95 % confidence intervals (CIs) for invasive breast cancer associated with alcohol consumed at or prior to completion of the baseline questionnaire. After a mean of 5.4 years of follow-up, we observed 259 incident cases of primary invasive breast cancer. Compared with non-users, the adjusted RRs were 1.06 (95 % CI 0.78-1.44) for ever use and 1.08 (0.79-1.47) for current alcohol use. For women in the highest versus lowest quintile of cumulative alcohol consumption, the RR was 0.94 (95 % CI 0.63-1.40; P trend = 0.65). Our findings suggest that alcohol consumption is not a risk factor for breast cancer among women with a BRCA1 or BRCA2 mutation.

Management of familial cancer: sequencing, surveillance and society

The clinical management of familial cancer begins with recognition of patterns of cancer occurrence suggestive of genetic susceptibility in a proband or pedigree, to enable subsequent investigation of the underlying DNA mutations. In this regard, next-generation sequencing of DNA continues to transform cancer diagnostics, by enabling screening for cancer-susceptibility genes in the context of known and emerging familial cancer syndromes. Increasingly, not only are candidate cancer genes sequenced, but also entire 'healthy' genomes are mapped in children with cancer and their family members. Although large-scale genomic analysis is considered intrinsic to the success of cancer research and discovery, a number of accompanying ethical and technical issues must be addressed before this approach can be adopted widely in personalized therapy. In this Perspectives article, we describe our views on how the emergence of new sequencing technologies and cancer surveillance strategies is altering the framework for the clinical management of hereditary cancer. Genetic counselling and disclosure issues are discussed, and strategies for approaching ethical dilemmas are proposed.

Realizing the promise of cancer predisposition genes

Genes in which germline mutations confer highly or moderately increased risks of cancer are called cancer predisposition genes. More than 100 of these genes have been identified, providing important scientific insights in many areas, particularly the mechanisms of cancer causation. Moreover, clinical utilization of cancer predisposition genes has had a substantial impact on diagnosis, optimized management and prevention of cancer. The recent transformative advances in DNA sequencing hold the promise of many more cancer predisposition gene discoveries, and greater and broader clinical applications. However, there is also considerable potential for incorrect inferences and inappropriate clinical applications. Realizing the promise of cancer predisposition genes for science and medicine will thus require careful navigation.

Timing of oral contraceptive use and the risk of breast cancer in BRCA1 mutation carriers

It is not clear if early oral contraceptive use increases the risk of breast cancer among young women with a breast cancer susceptibility gene 1 (BRCA1) mutation. Given the benefit of oral contraceptives for the prevention of ovarian cancer, estimating age-specific risk ratios for oral contraceptive use and breast cancer is important. We conducted a case-control study of 2,492 matched pairs of women with a deleterious BRCA1 mutation. Breast cancer cases and unaffected controls were matched on year of birth and country of residence. Detailed information about oral contraceptive use was collected from a routinely administered questionnaire. Conditional logistic regression was used to estimate the odds ratios (OR) and 95 % confidence intervals (CI) for the association between oral contraceptive and breast cancer, by age at first use and by age at diagnosis. Among BRCA1 mutation carriers, oral contraceptive use was significantly associated with an increased risk of breast cancer for women who started the pill prior to age 20 (OR 1.45; 95 % CI 1.20-1.75; P = 0.0001) and possibly between ages 20 and 25 as well (OR 1.19; 95 % CI 0.99-1.42; P = 0.06). The effect was limited to breast cancers diagnosed before age 40 (OR 1.40; 95 % CI 1.14-1.70; P = 0.001); the risk of early-onset breast cancer increased by 11 % with each additional year of pill use when initiated prior to age 20 (OR 1.11; 95 % CI 1.03-1.20; P = 0.008). There was no observed increase for women diagnosed at or after the age of 40 (OR 0.97; 95 % CI 0.79-1.20; P = 0.81). Oral contraceptive use before age 25 increases the risk of early-onset breast cancer among women with a BRCA1 mutation and the risk increases with duration of use. Caution should be taken when advising women with a BRCA1 mutation to take an oral contraceptive prior to age 25.

Alcohol Intake and Breast Cancer Risk: Weighing the Overall Evidence

Moderate alcohol consumption has been linked to an approximate 30-50% increased risk in breast cancer. Case-control and cohort studies have consistently observed this modest increase. We highlight recent evidence from molecular epidemiologic studies and studies of intermediate markers like mammographic density that provide additional evidence that this association is real and not solely explained by factors/correlates of the exposure and outcome present in non-randomized studies. We also review evidence from studies of higher risk women including BRCA1 and BRCA2 mutation carriers. Given the incidence of heart disease is higher than breast cancer and modest alcohol consumption is associated with reduced risk of heart disease, we examine the latest evidence to evaluate if alcohol reduction should be targeted to women at high risk for breast cancer. We also review the most recent evidence on the effect of alcohol use on tumor recurrence and survival for those diagnosed with breast cancer.

Alcohol Intake and Breast Cancer Risk: Weighing the Overall Evidence

Moderate alcohol consumption has been linked to an approximate 30-50% increased risk in breast cancer. Case-control and cohort studies have consistently observed this modest increase. We highlight recent evidence from molecular epidemiologic studies and studies of intermediate markers like mammographic density that provide additional evidence that this association is real and not solely explained by factors/correlates of the exposure and outcome present in non-randomized studies. We also review evidence from studies of higher risk women including BRCA1 and BRCA2 mutation carriers. Given the incidence of heart disease is higher than breast cancer and modest alcohol consumption is associated with reduced risk of heart disease, we examine the latest evidence to evaluate if alcohol reduction should be targeted to women at high risk for breast cancer. We also review the most recent evidence on the effect of alcohol use on tumor recurrence and survival for those diagnosed with breast cancer.

Does and should breast cancer genetic counselling include lifestyle advice?

To optimally inform counselees about their and their relatives' risks, information about lifestyle risk factors, e.g. physical activity and alcohol consumption, might be discussed in breast cancer genetic counselling. This study explored whether lifestyle was discussed, on whose initiative, whether information and/or advice was given, and whether discussion of lifestyle was related to counselees' characteristics and their causal attributions. First and follow-up consultations with 192 consecutive counselees for breast cancer genetic counselling were videotaped and coded for discussion of lifestyle topics. Counselees completed web-based questionnaires before the initial and after the final consultation. With 52 (27%) counselees lifestyle was discussed, either in the first, or the final consultation, or both. Counselees mostly raised the topic (60%). Counsellors provided information about lifestyle risk factors to 19% and lifestyle advice to 6% of the counselees. Discussion of lifestyle was not associated with counselees' characteristics or causal attributions. Post-counselling, more affected counselees considered lifestyle as a cause of their breast cancer (29%) compared to pre-counselling (15%; p = 0.003). Information and advice about lifestyle risk factors was infrequently provided, both with breast cancer unaffected and affected counselees and with those who did and did not consider their lifestyle as a cause of their breast cancer. Modifiable lifestyle factors could be discussed more frequently to optimally inform counselees about possible ways to reduce their risk. Counsellors should be educated about effects of lifestyle and research should be conducted on how to best integrate lifestyle information in breast cancer genetic counselling.

Risk factors for ovarian cancers with and without microsatellite instability

OBJECTIVE

The objective of this study was to evaluate the association between microsatellite instability (MSI) status and (1) ovarian cancer risk factors and (2) the distribution of the specific histologic subtypes in a population-based sample of epithelial ovarian cancers.

METHODS

Participants were drawn from 3 population-based studies of primary epithelial ovarian cancer. Tumor DNA was analyzed using 5 standardized microsatellite markers to assess MSI status. Patients were divided into 3 groups (MSI-high, MSI-low, and MSI-stable) according to National Cancer Institute criteria. We compared the prevalence of specific known risk and protective factors among the 3 subgroups, including body mass index, smoking history, parity, BRCA1 and BRCA2 mutation status, past oral contraceptive use, and tubal ligation. Similarly, we compared the distribution of the histologic subtypes among the 3 subgroups.

RESULTS

A total of 917 ovarian cancer patients were included. One hundred twenty-seven (13.8%) cancers were MSI-high. Subgroup analyses according to smoking, body mass index, parity, past oral contraceptive use, and past tubal ligation did not reveal any statistically significant differences among the groups. Among the 29 patients with BRCA1 mutations, 20.7% had MSI-high cancers compared with 5.9% among 17 BRCA2-mutation patients. The proportions of different ovarian cancer histologic findings among the various MSI subgroups were similar.

CONCLUSIONS

The prevalence of risk and protective factors among ovarian cancer patients is similar for cancers with and without MSI. The distributions of MSI do not differ significantly among ovarian cancers with different histologic findings. Ovarian cancer patients with BRCA1 mutations had a 21% rate of MSI-high tumors, compared with 6% among patients with BRCA2 mutations, but this difference was not statistically significant.

Cancer risks for BRCA1 and BRCA2 mutation carriers: results from prospective analysis of EMBRACE

BACKGROUND

Reliable estimates of cancer risk are critical for guiding management of BRCA1 and BRCA2 mutation carriers. The aims of this study were to derive penetrance estimates for breast cancer, ovarian cancer, and contralateral breast cancer in a prospective series of mutation carriers and to assess how these risks are modified by common breast cancer susceptibility alleles.

METHODS

Prospective cancer risks were estimated using a cohort of 978 BRCA1 and 909 BRCA2 carriers from the United Kingdom. Nine hundred eighty-eight women had no breast or ovarian cancer diagnosis at baseline, 1509 women were unaffected by ovarian cancer, and 651 had been diagnosed with unilateral breast cancer. Cumulative risks were obtained using Kaplan-Meier estimates. Associations between cancer risk and covariables of interest were evaluated using Cox regression. All statistical tests were two-sided.

RESULTS

The average cumulative risks by age 70 years for BRCA1 carriers were estimated to be 60% (95% confidence interval [CI] = 44% to 75%) for breast cancer, 59% (95% CI = 43% to 76%) for ovarian cancer, and 83% (95% CI = 69% to 94%) for contralateral breast cancer. For BRCA2 carriers, the corresponding risks were 55% (95% CI = 41% to 70%) for breast cancer, 16.5% (95% CI = 7.5% to 34%) for ovarian cancer, and 62% (95% CI = 44% to 79.5%) for contralateral breast cancer. BRCA2 carriers in the highest tertile of risk, defined by the joint genotype distribution of seven single nucleotide polymorphisms associated with breast cancer risk, were at statistically significantly higher risk of developing breast cancer than those in the lowest tertile (hazard ratio = 4.1, 95% CI = 1.2 to 14.5; P = .02).

CONCLUSIONS

Prospective risk estimates confirm that BRCA1 and BRCA2 carriers are at high risk of developing breast, ovarian, and contralateral breast cancer. Our results confirm findings from retrospective studies that common breast cancer susceptibility alleles in combination are predictive of breast cancer risk for BRCA2 carriers.

Breast cancer risk factors differ between Asian and white women with BRCA1/2 mutations

The prevalence and penetrance of BRCA1 and BRCA2 (BRCA1/2) mutations may differ between Asians and whites. We investigated BRCA1/2 mutations and cancer risk factors in a clinic-based sample. BRCA1/2 mutation carriers were enrolled from cancer genetics clinics in Hong Kong and California according to standardized entry criteria. We compared BRCA mutation position, cancer history, hormonal and reproductive exposures. We analyzed DNA samples for single-nucleotide polymorphisms reported to modify breast cancer risk. We performed logistic regression to identify independent predictors of breast cancer. Fifty Asian women and forty-nine white American women were enrolled. BRCA1 mutations were more common among whites (67 vs. 42 %, p = 0.02), and BRCA2 mutations among Asians (58 vs. 37 %, p = 0.04). More Asians had breast cancer (76 vs. 53 %, p = 0.03); more whites had relatives with breast cancer (86 vs. 50 %, p = 0.0003). More whites than Asians had breastfed (71 vs. 42 %, p = 0.005), had high BMI (median 24.3 vs. 21.2, p = 0.04), consumed alcohol (2 drinks/week vs. 0, p < 0.001), and had oophorectomy (61 vs. 34 %, p = 0.01). Asians had a higher frequency of risk-associated alleles in MAP3K1 (88 vs. 59 %, p = 0.005) and TOX3/TNRC9 (88 vs. 55 %, p = 0.0002). On logistic regression, MAP3K1 was associated with increased breast cancer risk for BRCA2, but not BRCA1 mutation carriers; breast density was associated with increased risk among Asians but not whites. We found significant differences in breast cancer risk factors between Asian and white BRCA1/2 mutation carriers. Further investigation of racial differences in BRCA1/2 mutation epidemiology could inform targeted cancer risk-reduction strategies.

Oophorectomy after menopause and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

BACKGROUND

To evaluate the effect of the cumulative number of ovulatory cycles and its contributing components on the risk of breast cancer among BRCA mutation carriers.

METHODS

We conducted a matched case-control study on 2,854 pairs of women with a BRCA1 or BRCA2 mutation. Conditional logistic regression was used to estimate the association between the number of ovulatory cycles and various exposures and the risk of breast cancer. Information from a subset of these women enrolled in a prospective cohort study was used to calculate age-specific breast cancer rates.

RESULTS

The annual risk of breast cancer decreased with the number of ovulatory cycles experienced (ρ = -0.69; P = 0.03). Age at menarche and duration of breastfeeding were inversely related with risk of breast cancer among BRCA1 (P(trend) < 0.0001) but not among BRCA2 (P(trend) ≥ 0.28) mutation carriers. The reduction in breast cancer risk associated with surgical menopause [OR, 0.52; 95% confidence interval (CI), 0.40-0.66; P(trend) < 0.0001] was greater than that associated with natural menopause (OR, 0.81; 95% CI, 0.62-1.07; P(trend) = 0.14). There was a highly significant reduction in breast cancer risk among women who had an oophorectomy after natural menopause (OR, 0.13; 95% CI, 0.02-0.54; P = 0.006).

CONCLUSIONS

These data challenge the hypothesis that breast cancer risk can be predicted by the lifetime number of ovulatory cycles in women with a BRCA mutation. Both pre- and postmenopausal oophorectomy protect against breast cancer.

IMPACT

Understanding the basis for the protective effect of oophorectomy has important implications for chemoprevention.

Variation in breast cancer risk with mutation position, smoking, alcohol, and chest X-ray history, in the French National BRCA1/2 carrier cohort (GENEPSO)

Germline mutations in BRCA1/2 confer a high risk of breast cancer (BC), but the magnitude of this risk varies according to various factors. Although controversial, there are data to support the hypothesis of allelic-risk heterogeneity. We assessed variation in BC risk according to the location of mutations recorded in the French study GENEPSO. Since the women in this study were selected from high-risk families, oversampling of affected women was eliminated by using a weighted Cox-regression model. Women were censored at the date of diagnosis when affected by any cancer, or the date of interview when unaffected. A total of 990 women were selected for the analysis: 379 were classified as affected, 611 as unaffected. For BRCA1, there was some evidence of a central region where the risk of BC is lower (codons 374-1161) (HR = 0.59, P = 0.04). For BRCA2, there was a strong evidence for a region at decreased risk (codons 957-1827) (HR = 0.35, P = 0.005) and for one at increased risk (codons 2546-2968) (HR = 3.56, P = 0.01). Moreover, we found an important association between radiation exposure from chest X-rays and BC risk (HR = 4.29, P < 10(-3)) and a positive association between smoking more than 21 pack-years and BC risk (HR = 2.09, P = 0.04). No significant variation in BC risk associated with chest X-ray exposure, smoking, and alcohol consumption was found according to the location of the mutation in BRCA1 and BRCA2. Our findings are consistent with those suggesting that the risk of BC is lower in the central regions of BRCA1/2. A new high-risk region in BRCA2 is described. Taking into account environmental and lifestyle modifiers, the location of mutations might be important in the clinical management of BRCA mutation carriers.

Interactions between environmental factors and polymorphisms in angiogenesis pathway genes in esophageal adenocarcinoma risk: a case-only study

BACKGROUND

Gastroesophageal reflux disease (GERD), higher body mass index (BMI), smoking, and genetic variants in angiogenic pathway genes have been individually associated with increased risk of esophageal adenocarcinoma. However, how angiogenic gene polymorphisms and environmental factors jointly affect esophageal adenocarcinoma development remains unclear.

METHODS

By using a case-only design (n = 335), the authors examined interactions between 141 functional/tagging angiogenic single nucleotide polymorphisms (SNPs) and environmental factors (GERD, BMI, smoking) in modulating esophageal adenocarcinoma risk. Gene-environment interactions were assessed by a 2-step approach. First, the authors applied random forest to screen for important SNPs that had either main or interaction effects. Second, they used case-only logistic regression to assess the effects of gene-environment interactions on esophageal adenocarcinoma risk, adjusting for covariates and false-discovery rate.

RESULTS

Random forest analyses identified 3 sets of SNPs (17 SNPs-GERD, 26 SNPs-smoking, and 34 SNPs-BMI) that had the highest importance scores. In subsequent logistic regression analyses, interactions between 2 SNPs (rs2295778 of HIF1AN, rs13337626 of TSC2) and GERD, 2 SNPs (rs2295778 of HIF1AN, rs2296188 of VEGFR1) and smoking, and 7 SNPs (rs2114039 of PDGRFA, rs2296188 of VEGFR1, rs11941492 of VEGFR1, rs17708574 of PDGFRB, rs7324547 of VEGFR1, rs17619601 of VEGFR1, and rs17625898 of VEGFR1) and BMI were significantly associated with esophageal adenocarcinoma development (all false-discovery rates ≤0.10). Moreover, these interactions tended to have SNP dose-response effects for increased esophageal adenocarcinoma risk with increasing number of combined risk genotypes.

CONCLUSIONS

These findings suggest that genetic variations in angiogenic genes may modify esophageal adenocarcinoma susceptibility through interactions with environmental factors in an SNP dose-response manner.