BRCA mutations do not up risk of colorectal cancer

Carriers of the BRCA1 and/or BRCA2 mutation do not appear to be at increased risk of colorectal cancer, according to the results of a recent systematic review and meta-analysis.

The investigators sought to determine the risk of colorectal cancer associated with BRCA carrier mutations. The incidence of colorectal cancer in carriers of BRCA mutation was the primary outcome, while secondary ones included the incidence in BRCA1 and BRCA2 carriers, Ashkenazi Jews, and age- and sex-matched cohorts.

Eleven studies met the eligibility criteria for the systematic review, with an overall population of 14,252 and 4,831 colorectal cancer identified. Of these, only nine studies were included in the meta-analysis.

No increase in incidence of colorectal cancer was observed among patients carrying a BRCA mutation (odds ratio, 1.03, 95 percent confidence interval, 0.80–1.32; p=0.82). There was also no increased likelihood of developing colorectal cancer after adjusting for Ashkenazi heritage and age and sex estimates (with no heterogeneity; I2, 0 percent).

“Carriers of the BRCA1 and/or BRCA2 mutation incur a lifetime risk of up to 85 percent for breast cancer, and between 20 and 40 percent for ovarian cancer,” the investigators noted.

“Efforts to estimate the lifetime risk of developing colorectal cancer for BRCA mutation carriers have produced conflicting results. Consequently, there are no formal guidelines regarding the need for bowel screening for individuals with BRCA1 and/or BRCA2 mutations,” they added.