Studies of familial pancreatic cancer (FPC) [149,150,151,152,153] and unselected series of pancreatic cancer [154,155,156] have also supported an association with BRCA2, and to a lesser extent, BRCA1. Overall, it appears that between 3% to 15% of families with FPC may have germline BRCA2 mutations, with risks increasing with more affected relatives.[149,150,151] Similarly, studies of unselected pancreatic cancers have reported BRCA2 mutation frequencies between 3% to 7%, with these numbers approaching 10% in those of Ashkenazi Jewish descent.[154,155,157] The lifetime risk of pancreatic cancer in BRCA2 carriers is estimated to be 3% to 5% [8,12] compared with an estimated lifetime risk of 0.5% by age 70 years in the general population. Other cancers associated with BRCA2 mutations in some, but not all, studies include melanoma, biliary cancers, and head and neck cancers, but these risks appear modest (<5% lifetime) and are less well studied.
Table 5. Spectrum of Cancers in BRCA1 and BRCA2 Mutation Carriers
a Refer to the PDQ summary on Genetics of Prostate Cancer for more information about the association of BRCA1 and BRCA2 with prostate cancer.
+++ Multiple studies demonstrated association and are relatively consistent.
++ Multiple studies and the predominance of the evidence are positive.
+ May be an association, predominantly single studies; smaller limited studies and/or inconsistent but weighted toward positive.
|Cancer Sites [6,7,8,12,55,142]||BRCA1 Mutation Carrier||BRCA2 Mutation Carrier|
|�||Strength of Evidence||Magnitude of Absolute Risk||Strength of Evidence||Magnitude of Absolute Risk|
|Ovary, fallopian tube, peritoneum||+++||High||+++||Moderate|
The first Breast Cancer Linkage Consortium study investigating cancer risks reported an excess of colorectal cancer in BRCA1 carriers (relative risk [RR] = 4.1; 95% CI, 2.4-7.2). This finding was supported by some,[6,7,159] but not all,[8,55,61,86,160,161,162] family-based studies. However, unselected series of colorectal cancer that have been exclusively performed in the Ashkenazi Jewish population have not shown elevated rates of BRCA1 or BRCA2 mutations.[163,164,165] Taken together, the data suggest little, if any, increased risk of colorectal cancer, and possibly only in specific population groups. Therefore, at this time, BRCA1 mutation carriers should adhere to population-screening recommendations for colorectal cancer.
No increased prevalence of hereditary BRCA mutations was found among 200 Jewish women with endometrial carcinoma or 56 unselected women with uterine papillary serous carcinoma.[166,167] (Refer to the Risk-reducing salpingo-oophorectomy section in the Ovarian cancer section of this summary for more information.)
Cancer risk in individuals who test negative for a known familial BRCA1/BRCA2 mutation