Association between Breast Cancer and the Risk of Colorectal Cancer: Systematic Review and Meta-Analysis.Lai JH, Park G, Gerson LB. Gastrointest Endosc. 2017 Apr 19. [Epub ahead of print]
BACKGROUND:The prior literature has suggested a potential increase in colorectal cancer (CRC) among patients with breast cancer.
METHODS:We performed a systematic review of the literature and included 37 retrospective cohort studies and 8 case-control studies. The primary aim was to determine the prevalence of CRC. Secondary aims included analysis of adenomatous polyps and analysis of CRC prevalence by age. We calculated pooled prevalence rates and odds ratios using random effects models with 95% confidence intervals (CI).RESULTS:We identified 1,055,917 subjects with breast cancer of which 9,097 cases of CRC were detected. The pooled event rate for CRC was 0.7% (95% CI, 0.6%-0.9%, I2=97%). Four case-control studies reported prevalence of CRC (N=17,873 breast cancer patients and 70,366 controls) including 46 cases of CRC in the breast cancer patients, and 272 CRC in the control subjects. (OR 1.2; 95% CI, 0.4%-3.7%; p=0.7). Six studies reported prevalence of advanced adenomas in breast cancer cases (N=1087) compared with controls (N=1356) with 62 cases of advanced adenomas in cases compared with 47 in the controls (OR 1.5; 95% CI, 0.97-2.2; p=0.07). In patients with breast cancer under age 50 (4 studies, N=64,706) the pooled OR was increased (2.5; 95% CI, 1.7-3.5; p=0.0). In 3 studies of women under age 45 (N=92,594) the risk was increased (OR 2.3; 95% CI, 1.7-2.6; p<0.001).CONCLUSIONS:Patients with breast cancer should not undergo CRC screening at intervals different from the general population. In breast cancer patients under age 50, CRC screening should be considered at age 45.