Individuals who were BRCA1 mutation carriers — but not those who were BRCA2 mutation carriers — were determined to be at increased risk for colorectal cancer, a systematic review and meta-analysis published in the Journal of the National Cancer Institute concluded.1

“Investigations of the associations with colorectal cancer have yielded conflicting results,” the study authors wrote. “The aim of our study was to synthesize the research on colorectal cancer risks in BRCA mutation carriers by means of a systematic review and quantitatively by means of meta-analyses overall and in subgroups of BRCA mutation carriers.”

To identify studies that would be eligible for review inclusion, the study researchers queried PubMed/MEDLINE, Embase, Cochrane, Scopus, and ProQuest Dissertation & Theses. The search yielded 18 studies suitable for examination; 14 of these studies were ultimately included in the meta-analysis.

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The appraisal showed that overall BRCA mutation carriers had a statistically significant increased risk of colorectal cancer (odds ratio [OR], 1.24; 95% confidence interval [CI], 1.02-1.51; P = .03). A subgroup analysis revealed that a BRCA1 mutation, specifically, was correlated with a higher risk of colorectal cancer (OR, 1.49; 95% CI, 1.19-1.85; P < .001), but a BRCA2 mutation, however, was not associated with the same risk (OR, 1.10; 95% CI, 0.77-1.58; P = .61).

Subgroup analyses of only the studies that reported estimates that had been adjusted for age and sex also showed that the presence of a BRCA1 mutation was associated with a higher risk of colorectal cancer (OR, 1.56; 95% CI, 1.23-1.98; P < .001). BRCA2, again, was not linked to increased risk for the disease (OR, 1.09; 95% CI; 0.75-1.58; P = .66).

“The meta-analysis results provide clinicians and health-care regulatory agencies with evidence of the increased risk of colorectal cancer in BRCA1 mutation carriers, but not in BRCA2,” the study authors concluded.


  1. Oh M, McBride A, Yun S, et al. BRCA1 and BRCA2 gene mutations and colorectal cancer risk: systematic review and meta-analysis [published online October 31, 2018]. J Natl Cancer Inst. doi: 10.1093/jnci/djy148