Contralateral breast cancer in BRCA1 and BRCA2 mutation carriers.

PURPOSE: To estimate the risk of contralateral breast cancer in BRCA1 and BRCA2 carriers after diagnosis and to determine which factors are predictive of the risk of a second primary breast cancer. PATIENTS AND METHODS: Patients included 491 women with stage I or stage II breast cancer, for whom a BRCA1 or BRCA2 mutation had been identified in the family. Patients were followed from the initial diagnosis of cancer until contralateral mastectomy, contralateral breast cancer, death, or last follow-up. RESULTS: The actuarial risk of contralateral breast cancer was 29.5% at 10 years. Factors that were predictive of a reduced risk were the presence of a BRCA2 mutation (v BRCA1 mutation; hazard ratio [HR], 0.73; 95% CI, 0.47 to 1.15); age 50 years or older at first diagnosis (v 相似文献   

Cancer Incidence in BRCA1 mutation carriers

BACKGROUND: Germline BRCA1 mutations confer a substantial lifetime risk of breast and ovarian cancer, but whether cancer at other sites is increased is less clear. To evaluate the risks of other cancers in BRCA1 mutation carriers, we conducted a cohort study of 11 847 individuals from 699 families segregating a BRCA1 mutation that were ascertained in 30 centers across Europe and North America. METHODS: The observed cancer incidence was compared with the expected cancer incidence based on population cancer rates. Relative risks (RRs) of each cancer type in BRCA1 carriers relative to risks for the general population were estimated by weighting individuals according to their estimated probability of being a mutation carrier. All statistical tests were two-sided. RESULTS: BRCA1 mutation carriers were at a statistically significantly increased risk for several cancers, including pancreatic cancer (RR = 2.26, 95% confidence interval [CI] = 1.26 to 4.06, P =.004) and cancer of the uterine body and cervix (uterine body RR = 2.65, 95% CI = 1.69 to 4.16, P<.001; cervix RR = 3.72, 95% CI = 2.26 to 6.10, P<.001). There was some evidence of an elevated risk of prostate cancer in mutation carriers younger than 65 years old (RR = 1.82, 95% CI = 1.01 to 3.29, P =.05) but not in those 65 years old or older (RR = 0.84, 95% CI = 0.53 to 1.33, P =.45). Overall, increases in the risk for cancer at sites other than the breast or ovary were small and evident in women (RR = 2.30, 95% CI = 1.93 to 2.75, P =.001) but not in men (RR = 0.95, 95% CI = 0.81 to 1.12, P =.58). CONCLUSIONS: In carriers of BRCA1 mutations, the overall increased risk of cancer at sites other than breast and ovary is small and is observed in women but generally not in men. BRCA1 mutations may confer increased risks of other abdominal cancers in women and increased risks of pancreatic cancer in men and women.     

Tamoxifen and contralateral breast cancer in BRCA1 and BRCA2 carriers: an update

Women with a mutation in BRCA1 or BRCA2 face a lifetime risk of breast cancer of approximately 80%, and following the first diagnosis the 10-year risk of contralateral breast cancer is approximately 30%. It has been shown that both tamoxifen and oophorectomy prevent contralateral breast cancer, but it is not clear whether there is a benefit in giving tamoxifen to women who have previously undergone an oophorectomy. Furthermore, the relative degree of protection in BRCA1 and BRCA2 carriers has not been well evaluated. We studied 285 women with bilateral breast cancer and a BRCA1 or BRCA2 mutation, and 751 control women with unilateral breast cancer and a BRCA1 or BRCA2 mutation in a matched case-control study. Control women were of similar age and had a similar age of diagnosis of breast cancer and had been followed for as long as the case for a second primary breast cancer. The history of tamoxifen use for treating the first breast cancer was compared between bilateral and unilateral cases. The multivariate odds ratio for contralateral breast cancer associated with tamoxifen use was 0.50 for carriers of BRCA1 mutations (95% CI, 0.30-0.85) and was 0.42 for carriers of BRCA2 mutations (95% CI, 0.17-1.02). The protective effect of tamoxifen was not seen among women who had undergone an oophorectomy (OR = 0.83; 95%CI, 0.24-2.89) but this subgroup was small. In contrast, a strong protective effect of tamoxifen was apparent among women who were premenopausal or who had undergone natural menopause (OR = 0.44; 95% CI, 0.27-0.65).     

Effect of pregnancy as a risk factor for breast cancer in BRCA1/BRCA2 mutation carriers

Early age at first birth and multiparity have been associated with a decrease in the risk of breast cancer in women in the general population. We examined whether this relationship is also present in women at high risk of breast cancer due to the presence of a mutation in either of the 2 breast cancer susceptibility genes, BRCA1 or BRCA2. We performed a matched case-control study of 1,260 pairs of women with known BRCA1 or BRCA2 mutations, recruited from North America, Europe and Israel. Women who had been diagnosed with breast cancer were matched with unaffected control subjects for year of birth, country of residence, and mutation (BRCA1 or BRCA2). Study subjects completed a questionnaire detailing their reproductive histories. Odds ratios (ORs) and 95% confidence intervals (CIs) were derived by conditional logistic regression. Among BRCA1 carriers, parity per se was not associated with the risk of breast cancer (OR for parous vs. nulliparous = 0.94; 95% CI = 0.75-1.19; p = 0.62). However, women with a BRCA1 mutation and 4 or more children had a 38% decrease in breast cancer risk compared to nulliparous women (OR = 0.62; 95% CI = 0.41-0.94). In contrast, among BRCA2 carriers, increasing parity was associated with an increased risk of breast cancer; women with 2 or more children were at approximately 1.5 times the risk of breast cancer as nulliparous women (OR = 1.53; 95% CI = 1.01-2.32; p = 0.05). Among women with BRCA2 mutations and who were younger than age 50, the (adjusted) risk of breast cancer increased by 17% with each additional birth (OR = 1.17; 95% CI = 1.01-1.36; p = 0.03). There was no significant increase in the risk of breast cancer among BRCA2 carriers older than 50 (OR for each additional birth = 0.97; 95% CI = 0.58-1.53; p = 0.92). In the 2-year period following a birth, the risk of breast cancer in a BRCA2 carrier was increased by 70% compared to nulliparous controls (OR = 1.70; 95% CI = 0.97-3.0). There was a much smaller increase in breast cancer risk among BRCA2 carriers whose last birth was 5 or more years in the past (OR = 1.24; 95% CI = 0.79-1.95). A modest reduction in risk of breast cancer was observed among BRCA1 carriers with 4 or more births. Among BRCA2 carriers, increasing parity was associated with a significant increase in the risk of breast cancer before age 50 and this increase was greatest in the 2-year period following a pregnancy.     

Prevalence and penetrance of BRCA1 and BRCA2 gene mutations in unselected Ashkenazi Jewish women with breast cancer.

BACKGROUND: Approximately 2.0%-2.5% of Ashkenazi Jewish women carry one of three founding mutations in the BRCA1 and BRCA2 genes, and each mutation is associated with a high lifetime risk of invasive breast cancer. We investigated the extent to which these three mutations contribute to breast cancer incidence in the Ashkenazi Jewish population. METHODS: We ascertained 457 Jewish women with prevalent cases of breast cancer who were unselected for age or family history of the disease; 412 of these women were tested for the three founder mutations (case patients). Control subjects consisted of 360 non-Jewish women with breast cancer (control patients) and 380 healthy Jewish women with no history of cancer (control subjects). RESULTS: Mutations were found in 48 (11.7%) of 412 Jewish case patients. Forty-six of 48 mutations occurred in women with early-onset breast cancer (<50 years) or a history of ovarian or early-onset breast cancer in a first-, second-, or third-degree relative. The estimated penetrance to age 70 years for breast cancer was 59.9% for the BRCA1 gene mutations and 28.3% for the BRCA2 gene mutation. Compared with Jewish control subjects, the relative risk (RR) of breast cancer for first-degree relatives of mutation carriers was 5.16 (95% confidence interval [CI] = 3.14-8. 48), but risk was also increased for relatives of noncarriers (RR = 1.66; 95% CI = 1.18-2.33). The RR of prostate cancer for first-degree relatives of Jewish case patients was 3.36 (95% CI = 1. 49-7.56). CONCLUSIONS: Approximately 12% of breast cancers in the Ashkenazi Jewish population are attributable to mutations in the BRCA1 or BRCA2 gene. Genetic testing may be useful when Jewish women with breast cancer are diagnosed before age 50 years or have a close relative with ovarian or early-onset breast cancer. An association between breast and prostate cancers was observed in our study population.     

Oral contraceptive use and risk of early-onset breast cancer in carriers and noncarriers of BRCA1 and BRCA2 mutations.

BACKGROUND: Recent oral contraceptive use has been associated with a small increase in breast cancer risk and a substantial decrease in ovarian cancer risk. The effects on risks for women with germ line mutations in BRCA1 or BRCA2 are unclear.METHODS: Subjects were population-based samples of Caucasian women that comprised 1,156 incident cases of invasive breast cancer diagnosed before age 40 (including 47 BRCA1 and 36 BRCA2 mutation carriers) and 815 controls from the San Francisco Bay area, California, Ontario, Canada, and Melbourne and Sydney, Australia. Relative risks by carrier status were estimated using unconditional logistic regression, comparing oral contraceptive use in case groups defined by mutation status with that in controls.RESULTS: After adjustment for potential confounders, oral contraceptive use for at least 12 months was associated with decreased breast cancer risk for BRCA1 mutation carriers [odds ratio (OR), 0.22; 95% confidence interval (CI), 0.10-0.49; P < 0.001], but not for BRCA2 mutation carriers (OR, 1.02; 95% CI, 0.34-3.09) or noncarriers (OR, 0.93; 95% CI, 0.69-1.24). First use during or before 1975 was associated with increased risk for noncarriers (OR, 1.52 per year of use before 1976; 95% CI, 1.22-1.91; P < 0.001).CONCLUSIONS: There was no evidence that use of current low-dose oral contraceptive formulations increases risk of early-onset breast cancer for mutation carriers, and there may be a reduced risk for BRCA1 mutation carriers. Because current formulations of oral contraceptives may reduce, or at least not exacerbate, ovarian cancer risk for mutation carriers, they should not be contraindicated for a woman with a germ line mutation in BRCA1 or BRCA2.     

Breastfeeding and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

INTRODUCTION: Breastfeeding has been inversely related to breast cancer risk in the general population. Clarifying the role of breastfeeding among women with a BRCA1 or BRCA2 mutation may be helpful for risk assessment and for recommendations regarding prevention. We present an updated analysis of breastfeeding and risk of breast cancer using a large matched sample of BRCA mutation carriers. METHODS: We conducted a case-control study of 1,665 pairs of women with a deleterious mutation in either BRCA1 (n = 1,243 pairs) or BRCA2 (n = 422 pairs). Breast cancer cases and unaffected controls were matched on year of birth, mutation status, country of residence and parity. Information about reproductive factors, including breastfeeding for each live birth, was collected from a routinely administered questionnaire. Conditional logistic regression was used to estimate the association between ever having breastfed, as well as total duration of breastfeeding, and the risk of breast cancer. RESULTS: Among BRCA1 mutation carriers, breastfeeding for at least one year was associated with a 32% reduction in risk (OR = 0.68; 95% CI 0.52 to 0.91; P = 0.008); breastfeeding for two or more years conferred a greater reduction in risk (OR = 0.51; 95% CI 0.35 to 0.74). Among BRCA2 mutation carriers, there was no significant association between breastfeeding for at least one year and breast cancer risk (OR = 0.83; 95% CI 0.53 to 1.31; P = 0.43). CONCLUSIONS: These data extend our previous findings that breastfeeding protects against BRCA1-, but not BRCA2-associated breast cancer. BRCA mutation carriers should be advised of the benefit of breastfeeding in terms of reducing breast cancer risk.     

The joint effect of smoking and AIB1 on breast cancer risk in BRCA1 mutation carriers

Women with BRCA1 mutations are at an elevated risk for breast cancer. AIB1 (NCOA3/SRC3) genotype and smoking may alter this risk. We examined the differences in breast cancer risk by AIB1 polyglutamine repeat polymorphism and pre-diagnosis smoking habits for BRCA1 mutation carriers to determine if there was an interaction between smoking and AIB1 genotype. Multivariate Cox proportional hazards regression was used with 316 female BRCA1 mutation carriers to model breast cancer risk. Ever having smoked was associated with a decreased breast cancer risk [Hazard Ratio (HR) = 0.63, 95% CI, 0.47-0.87]. A dose-response relationship between number of pack-years smoked and breast cancer risk was also found for women who smoked <20 pack years of cigarettes (HR = 0.72, 95% CI, 0.52-1.00) and for women who smoked >/=20 pack years (HR = 0.41, 95% CI, 0.23-0.71; P for trend = 0.0007). Women with a 28 repeat allele for AIB1 had a significantly reduced risk of breast cancer (HR = 0.72, 95% CI, 0.51-1.00). Women who smoked >/=20 pack-years with a 28 repeat allele had an even greater reduced risk of breast cancer (HR = 0.19, 95% CI, 0.07-0.54) compared to women who were never smokers with no 28 allele. Since AIB1 appears to modulate the effect of endogenous hormones via the estrogen receptor, and smoking affects circulating hormone levels, these results support evidence that steroid hormones play an important role in breast carcinogenesis in BRCA1 mutation carriers, and suggest mechanisms for developing novel cancer prevention strategies for BRCA1 mutation carriers.     

BRCA1 and BRCA2 mutation carriers, oral contraceptive use, and breast cancer before age 50.

BACKGROUND: Understanding the effect of oral contraceptives on risk of breast cancer in BRCA1 or BRCA2 mutation carriers is important because oral contraceptive use is a common, modifiable practice. METHODS: We studied 497 BRCA1 and 307 BRCA2 mutation carriers, of whom 195 and 128, respectively, had been diagnosed with breast cancer. Case-control analyses were conducted using unconditional logistic regression with adjustments for family history and familial relationships and were restricted to subjects with a reference age under 50 years. RESULTS: For BRCA1 mutation carriers, there was no significant association between risk of breast cancer and use of oral contraceptives for at least 1 year [odds ratio (OR), 0.77; 95% confidence interval (95% CI), 0.53-1.12] or duration of oral contraceptive use (P(trend) = 0.62). For BRCA2 mutation carriers, there was no association with use of oral contraceptives for at least 1 year (OR, 1.62; 95% CI, 0.90-2.92); however, there was an association of elevated risk with oral contraceptive use for at least 5 years (OR, 2.06; 95% CI, 1.08-3.94) and with duration of use (OR(trend) per year of use, 1.08; P = 0.008). Similar results were obtained when we considered only use of oral contraceptives that first started in 1975 or later. CONCLUSIONS: We found no evidence overall that use of oral contraceptives for at least 1 year is associated with breast cancer risk for BRCA1 and BRCA2 mutation carriers before age 50. For BRCA2 mutation carriers, use of oral contraceptives may be associated with an increased risk of breast cancer among women who use them for at least 5 years. Further studies reporting results separately for BRCA1 and BRCA2 mutation carriers are needed to resolve this important issue.     

Coffee consumption and breast cancer risk among BRCA1 and BRCA2 mutation carriers

Although there are several plausible biologic mechanisms whereby coffee consumption might influence the risk of breast cancer, epidemiologic evidence is limited. We assessed the association between coffee consumption and breast cancer risk among high-risk women who carry BRCA mutations. We performed a matched case-control analysis on 1,690 women with a BRCA1 or BRCA2 mutation from 40 centers in 4 countries. Average lifetime coffee consumption was estimated via a self-administered questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression. After adjustment for potential confounders, the ORs for breast cancer in BRCA carriers who habitually drank 0, 1-3, 4-5 and 6 or more cups of coffee were 1.00, 0.90 (95% CI 0.72-1.12), 0.75 (95% CI 0.47-1.19) and 0.31 (95% CI 0.13-0.71; p-trend = 0.02). The effect was limited to the consumption of caffeinated coffee. These results suggest that among women with BRCA gene mutation, coffee consumption is unlikely to be harmful and that high levels of consumption may in fact be related to reduced breast cancer risk.     

Breast cancer risk after bilateral prophylactic oophorectomy in BRCA1 mutation carriers.

BACKGROUND: The availability of genetic testing for inherited mutations in the BRCA1 gene provides potentially valuable information to women at high risk of breast or ovarian cancer; however, carriers of BRCA1 mutations have few clinical management options to reduce their cancer risk. Decreases in ovarian hormone exposure following bilateral prophylactic oophorectomy (i.e., surgical removal of the ovaries) may alter cancer risk in BRCA1 mutation carriers. This study was undertaken to evaluate whether bilateral prophylactic oophorectomy is associated with a reduction in breast cancer risk in BRCA1 mutation carriers. METHODS: We studied a cohort of women with disease-associated germline BRCA1 mutations who were assembled from five North American centers. Surgery subjects (n = 43) included women with BRCA1 mutations who underwent bilateral prophylactic oophorectomy but had no history of breast or ovarian cancer and had not had a prophylactic mastectomy. Control subjects included women with BRCA1 mutations who had no history of oophorectomy and no history of breast or ovarian cancer (n = 79). Control subjects were matched to the surgery subjects according to center and year of birth. RESULTS: We found a statistically significant reduction in breast cancer risk after bilateral prophylactic oophorectomy, with an adjusted hazard ratio (HR) of 0.53 (95% confidence interval [CI] = 0.33-0.84). This risk reduction was even greater in women who were followed 5-10 (HR = 0. 28; 95% CI = 0.08-0.94) or at least 10 (HR = 0.33; 95% CI = 0.12-0.91) years after surgery. Use of hormone replacement therapy did not negate the reduction in breast cancer risk after surgery. CONCLUSIONS: Bilateral prophylactic oophorectomy is associated with a reduced breast cancer risk in women who carry a BRCA1 mutation. The likely mechanism is reduction of ovarian hormone exposure. These findings have implications for the management of breast cancer risk in women who carry BRCA1 mutations.     

Modification of BRCA1- and BRCA2-associated breast cancer risk by AIB1 genotype and reproductive history.

Women who have inherited a germ-line mutation in the BRCA1 or BRCA2 (BRCA1/2) genes have a greatly increased risk of developing breast cancer compared with the general population. However, there is also substantial interindividual variability in the occurrence of breast cancer among BRCA1/2 mutation carriers. We hypothesize that genes involved in endocrine signaling may modify the BRCA1/2-associated age-specific breast cancer penetrance. We studied the effect of alleles at the AIB1 gene using a matched case-control sample of 448 women with germ-line BRCA1/2 mutations. We found that these women were at significantly higher breast cancer risk if they carried alleles with at least 28 or 29 polyglutamine repeats at AIB1, compared with women who carried alleles with fewer polyglutamine repeats [odds ratio (OR), 1.59; 95% confidence interval (CI), 1.03-2.47 and OR, 2.85; 95% CI, 1.64-4.96, respectively]. Late age at first live birth and nulliparity have been associated with increased breast cancer risk. We observed increases in BRCA1/2-associated breast cancer risk in women who were either nulliparous or had their first live birth after age 30 (OR, 3.06; 95% CI, 1.52-6.16). Women were at significantly increased risk if they were nulliparous or had a late age at first live birth and had AIB1 alleles no shorter than 28 or 29 or more AIB1 polyglutamine repeats (OR, 4.62; 95% CI, 2.02-10.56 and OR, 6.97; 95% CI, 1.71-28.43, respectively) than women with none of these risk factors. Our results support the hypothesis that pathways involving endocrine signaling, as measured through AIB1 genotype and reproductive history, may have a substantial effect on BRCA1/2-associated breast cancer risk.     

Breast cancer risk in BRCA1 and BRCA2 mutation carriers and polyglutamine repeat length in the AIB1 gene

Marked variation in phenotypic expression among BRCA1 and BRCA2 mutation carriers may be partly explained by modifier genes that influence mutation penetrance. Variation in CAG/CAA repeat lengths coding for stretches of glutamines in the C-terminus of the AIB1 protein (amplified in breast cancer 1, a steroid receptor coactivator) has been proposed to modify the breast cancer risk in women carrying germline BRCA1 mutations. We genotyped the AIB1 repeat length polymorphism from the genomic DNA of a group of 851 BRCA1 and 324 BRCA2 female germline mutation carriers to estimate an association with breast cancer risk modification. Hazard ratios (HR) were calculated using a Cox proportional hazards model. For BRCA1 and BRCA2 mutation carriers, analyzed separately and together, we found that women who carried alleles with 28 or more polyglutamine repeats had no increased risk of breast cancer compared to those who carried alleles with fewer repeats (HR for BRCA1/2 carriers = 0.88, 95% CI [confidence interval] = 0.75-1.04). Analyzing average repeat lengths as a continuous variable showed no excess risk of breast cancer (BC) in BRCA1 or BRCA2 mutation carriers (HR for average repeat length in BRCA1/2 carriers = 1.01, 95% CI = 0.92-1.11). These results strongly suggest that contrary to previous studies, there is no significant effect of AIB1 genetic variation on BC risk in BRCA1 mutation carriers and provide an indication that there is also no strong risk modification in BRCA2 carriers.     

Estimates of the likely prophylactic effect of tamoxifen in women with high risk BRCA1 and BRCA2 mutations

The development of breast cancer control strategies in women at high genetic risk of breast cancer is an important issue. The likely benefit of chemopreventive approaches is of particular interest. Tamoxifen tends to be more effective in both prevention and treatment of oestrogen receptor positive tumours than oestrogen receptor negative. In this study, we combine the oestrogen-receptor specific effects of tamoxifen from randomized preventive or therapeutic trials with the oestrogen receptor status of tumours in BRCA1 and BRCA2 mutation positive women from published tumour surveys to obtain estimates of the likely effect of tamoxifen administration in mutation carriers. We used a simple two-stage procedure to estimate the benefit as a weighted average of the effect on oestrogen receptor positive tumours and oestrogen receptor negative, and using a more complex hierarchical modelling approach. Using the simple procedure and deriving the estimates of benefit from both primary prevention and therapeutic trials, we obtain an estimated reduction in risk of breast cancer from administration of tamoxifen in BRCA1 mutation positive women of 13% (RR=0.87, 95% CI 0.68--1.11). The corresponding estimated reduction in BRCA2 mutation positive women was 27% (RR=0.73, 95% CI 0.59--0.90). Using the more complex models gave essentially the same results. Using only the primary prevention trials gave smaller estimates of benefit in BRCA1 carriers but larger estimates in BRCA2, in both cases with wider confidence intervals. The benefit of prophylactic use of tamoxifen in BRCA1 mutation carriers is likely to be modest, and the effect in BRCA2 mutation carriers somewhat greater.     

Family history of cancer and cancer risks in women with BRCA1 or BRCA2 mutations

Women who carry a deleterious mutation in BRCA1 or BRCA2 have high lifetime risks of breast and ovarian cancers. However, the influence of a family history of these cancers on these risks in women with BRCA mutations is unclear. We calculated cancer incidence rates for a multinational cohort comprising 3011 women with BRCA1 or BRCA2 mutations who were followed up for a mean of 3.9 years, during which time 243 incident breast or ovarian cancers were recorded. The 10-year cumulative risks of breast cancer were 18.1% (95% confidence interval [CI] = 13.3% to 22.8%) for women with a BRCA1 mutation and 15.2% (95% CI = 9.1% to 21.2%) for women with a BRCA2 mutation. Among women with a BRCA1 mutation, the risk of breast cancer increased by 1.2-fold for each first-degree relative with breast cancer before age 50 years (hazard ratio [HR] = 1.21; 95% confidence interval [CI] = 0.94 to 1.57) and the risk of ovarian cancer increased by 1.6 fold for each first- or second-degree relative with ovarian cancer (HR = 1.61; 95% CI = 1.21 to 2.14). Among women with a BRCA2 mutation, the risk of breast cancer increased by 1.7-fold for each first-degree relative younger than 50 years with breast cancer (HR = 1.67; 95% CI = 1.04 to 2.07).     

Population-based estimate of the average age-specific cumulative risk of breast cancer for a defined set of protein-truncating mutations in BRCA1 and BRCA2. Australian Breast Cancer Family Study.

The average breast cancer risk for carriers of a germ-line mutation in BRCA1 or BRCA2 (penetrance) has been estimated from the multiple-case families collected by the Breast Cancer Linkage Consortium (BCLC) to be approximately 80% to age 70. However, women now being tested for these mutations do not necessarily have the intense family history of the BCLC families. Testing for protein-truncating mutations in exons 2, 11, and 20 of BRCA1 and exons 10 and 11 of BRCA2 was conducted in a population-based sample of 388 Australian women with breast cancer diagnosed before age 40. Onset of breast cancer was analyzed in the known and potential mutation-carrying first- and second-degree female relatives of cases found to carry a mutation. Of the 18 mutation-carrying cases (9 BRCA1 and 9 BRCA2), only 5 (1 BRCA1 and 4 BRCA2) had at least one affected relative, so family history of breast cancer was not a strong predictor of mutation status in this setting. The risk in mutation carriers was, on average, 9 times the population risk [95% confidence interval (CI), 4-23; P < 0.001]. Penetrance to age 70 was 40% (95% CI, 15-65%), about half that estimated from BCLC families. By extrapolation, approximately 6% (95% CI, 2-20%) of breast cancer before age 40 may be caused by protein-truncating mutations in BRCA1 or BRCA2. Breast cancer risk in BRCA1 or BRCA2 mutation carriers may be modified by other genetic or environmental factors. Genetic counselors may need to take into account the family history of the consultand.     

Breast conservation therapy for invasive breast cancer in Ashkenazi women with BRCA gene founder mutations

BACKGROUND: Germline mutations in the BRCA1 and BRCA2 genes are associated with an increased risk of breast cancer. Whether women with breast cancer who have inherited mutations in these genes have a different outcome after breast conservation therapy than women with "sporadic" cancer is unresolved. Consequently, we compared the outcomes after breast conservation therapy in Ashkenazi women with or without germline mutations in BRCA1 and/or BRCA2 (hereafter called BRCA). METHODS: We studied 305 women of Ashkenazi Jewish descent undergoing breast-conserving treatment for 329 invasive breast cancers. We reviewed their clinical records, retrieved their archival tissue samples, and tested those samples for the founder mutations BRCA1 185delAG, BRCA1 5382insC, and BRCA2 6174delT. Genetic results were linked to clinical data and outcomes by univariate and multivariate analyses. All Pvalues are two-sided. RESULTS: We detected mutations in BRCA genes in 28 of 305 women. Women with BRCA mutations were more likely to be diagnosed with cancer before the age of 50 years (P<.001) and to have lymph node involvement (P =.04). Ipsilateral breast tumor recurrence was more common in women with BRCA mutations, although this did not reach statistical significance (relative risk [RR] = 1.79; 95% confidence interval [CI] = 0.64-5.03). Women with mutations were more likely to develop contralateral breast cancer (RR = 3.50; 95% CI = 1.78-8.74; P =.001). Distant disease-free survival was shorter in women with mutations (66.2% versus 84.3% at 10 years; P =.05), as was breast cancer-specific survival (71.9% versus 87.2% at 10 years; P =.02). Tumor stage and nodal status, but not mutation status, were predictive of distant disease-free and breast cancer-specific survival in multivariate analysis. CONCLUSIONS: Women with BRCA founder mutations are at increased risk for breast cancer-related events after breast conservation. However, mutation status is not an independent predictor of survival and should not influence decisions regarding adjuvant therapy. The increased contralateral breast cancer risk in women heterozygous for BRCA mutations mandates careful surveillance.     

Polyglutamine repeat length in the AIB1 gene modifies breast cancer susceptibility in BRCA1 carriers

Variation in the penetrance estimates for BRCA1 and BRCA2 mutation carriers suggests that other factors may modify cancer risk from specific mutations. One possible mechanism is an epigenetic effect of polymorphisms in other genes. Genes involved in hormonal signal transduction are possible candidates. The AIB1 gene, an estrogen receptor (ER) coactivator, is frequently amplified in breast and ovarian tumors. Variation of a CAG repeat length has been reported within this gene that encodes a polyglutamine repeat in the C-terminus of the protein. Three hundred eleven BRCA1/2 mutation carriers (257 were of Ashkenazi origin) were genotyped for the AIB1 polyglutamine repeat. Relative risks (RR) were estimated using a maximum likelihood approach. The estimated breast cancer (BC) RR per average repeat length adjusted for population type (Ashkenazi vs. non-Ashkenazi) was 1.15 (95% CI = 1.02-1.30; p = 0.01) for BRCA1/2 carriers, and 1.25 (95% CI = 1.09-1.42; p = 0.001) when analysis was restricted to BRCA1 carriers. RR of BC was 1.17 (95% CI = 0.91-1.74), for individuals with 2 alleles >/=29 polyglutamine repeats and 0.78 (95% CI = 0.50-1.16) for those with at least 1 allele of /=29 repeats respectively (p = 0.025). These results indicate significant association of the risk for BC in carriers of BRCA1 mutations with the polyglutamine chain of the AIB1 gene. Longer repeat length correlates with elevated risk, whereas in carriers of a shorter AIB1 allele BC risk was reduced. The AIB1 polyglutamine length did not affect BC risk among BRCA2 mutation carriers.     

Family history of breast and ovarian cancers and BRCA1 and BRCA2 mutations in a population-based series of early-onset breast cancer

BACKGROUND: BRCA1 and BRCA2 are the two major susceptibility genes involved in hereditary breast cancer. This study was undertaken to provide reliable population-based estimates of genetic influence and to characterize the nature and prevalence of BRCA1 and BRCA2 germline mutations in early-onset breast cancer. METHODS: In a series comprising all women diagnosed with breast cancer under the age of 41 years in southern Sweden during 1990 through 1995 (n = 262), family history of cancer was evaluated in 95% (n = 250) of the case subjects and germline mutations in BRCA1 and BRCA2 were analyzed in 89% (n = 234). All statistical tests were two-sided. RESULTS: A total of 97 case subjects had at least one first- or second-degree relative with breast or ovarian cancer; 34 (14%; 95% confidence interval [CI] = 9.6% to 18%) cases had at least two first- or second-degree relatives, 22 (8.8%; 95%CI = 5.3% to 12%) had one first-degree relative, and 41 (16%; 95% CI = 12% to 21%) had one second-degree relative with either cancer. If two females affected with breast or ovarian cancer who were related through an unaffected male were also defined as first-degree relatives, then a higher number of case subjects, 120 (48%; 95% CI = 42% to 54%), had at least one first-degree or second-degree relative with breast or ovarian cancer. Sixteen (6.8%; 95% CI = 4.0% to 11%) BRCA1 mutation carriers and five (2.1%; 95% CI = 0.70% to 4.9%) BRCA2 mutation carriers were identified. Among case subjects with one first- or more than one first- or second-degree relative with breast or ovarian cancer, BRCA mutations were more frequent (P<.001) than among the case subjects without this degree of family history. BRCA mutations were also statistically significantly more common among women with bilateral breast cancer than among women with unilateral breast cancer (P =.002). BRCA mutations were more common among younger case subjects than among older ones (P =.0027). CONCLUSIONS: Almost half (48%) of women in southern Sweden with early-onset breast cancer have some family history of breast or ovarian cancer, and 9.0% of early-onset breast cancer cases are associated with a germline mutation in BRCA1 or BRCA2. Mutation carriers were more prevalent among young women, women with at least one first- or second-degree relative with breast or ovarian cancer, and women with bilateral breast cancer.     

Smoking and the risk of breast cancer in BRCA1 and BRCA2 carriers: an update

Among women with a mutation in BRCA1 or BRCA2, the risk of breast cancer is high, but it may be modified by exogenous and endogenous factors. There is concern that exposure to carcinogens in cigarette smoke may increase the risk of cancer in mutation carriers. We conducted a matched case–control study of 2,538 cases of breast cancer among women with a BRCA1 (n = 1,920) or a BRCA2 (n = 618) mutation. One non-affected mutation carrier control was selected for each case, matched on mutation, country of birth, and year of birth. Odds ratios were calculated using conditional logistic regression, adjusted for oral contraceptive use and parity. Ever-smoking was not associated with an increased breast cancer risk among BRCA1 carriers (OR = 1.09; 95% CI 0.95–1.24) or among BRCA2 carriers (OR = 0.81; 95% CI 0.63–1.05). The result did not differ when cases were restricted to women who completed the questionnaire within two years of diagnosis. A modest, but significant increase in risk was seen among BRCA1 carriers with a past history of smoking (OR = 1.27; 95% CI 1.06–1.50), but not among current smokers (OR = 0.95; 0.81–1.12). There appears to be no increase in the risk of breast cancer associated with current smoking in BRCA1 or BRCA2 carriers. There is a possibility of an increased risk of breast cancer among BRCA1 carriers associated with past smoking. There may be different effects of carcinogens in BRCA mutation carriers, depending upon the timing of exposure. Other members of the Hereditary Breast Cancer Clinical Study Group: Olufunmilayo Olopade, Shelly Cummings, Fergus Couch, Barry Rosen, Dominique Stoppa-Lyonnet, Ruth Gershoni-Baruch, David Horsman, Teresa Wagner, Howard Saal, Ellen Warner, Wendy Meschino, Kenneth Offit, Amber Trivedi, Michael Osborne, Dawna Gilchrist, Charis Eng, Jeffrey Weitzel, Wendy McKinnon, Marie Wood, Christine Maugard, Barbari Pasini, Peter Ainsworth, Kevin Sweet, Boris Pasche, Beth Karlan, Raluca N. Kurz, Anna Tulman, Ed Lemire, Jane Mclennan, Gareth Evans, Tomas Byrski, Tomas Huzarski, Jacek Gronwald, Bohdan Gorski, Eitan Friedman, Andrea Eisen, Mary Daly, Judy Garber, Sofia Merajver.