ARE WOMEN WITH BREAST, ENDOMETRIAL, OR OVARIAN-CANCER AT INCREASED RISK FOR COLORECTAL-CANCER

Objectives: Evidence is accumulating supporting the use of screening f or colorectal cancer. Patients at higher risk for colorectal cancer ar e more likely to benefit from screening. Women with breast, endometria l, or ovarian cancer are often classified as at high risk for subseque nt colorectal cancer, and are urged to undergo screening, but the basi s for this is uncertain. Methods: We performed a meta-analysis of publ ished data to assess the risk of colorectal cancer after these cancers . Results: Based on 154,270 women and 779,251 person-yr of observation (PYO) after breast cancer, 37,266 women and 229,498 PYO after endomet rial cancer, and 41,366 women and 126,688 PYO after ovarian cancer, th e age-adjusted relative risk (95%CI) for colorectal cancer after breas t cancer was 1.1 (1.07, 1.19), after endometrial cancer 1.4 (1.32, 1.5 5), and after ovarian cancer 1.6 (1.40, 1.80). Conclusions: 1) Women w ith a history of breast, endometrial, or ovarian cancer are at a stati stically significant increased risk for subsequent colorectal cancer. 2) Women with a history of endometrial or ovarian cancer are at higher risk than are women with breast cancer, but ascertainment bias from h eightened medical surveillance after the diagnosis of a gynecologic ma lignancy may contribute to this observed increase in risk. 3) The asso ciation between these cancers and colorectal cancer suggests common et iologic factors, either environmental or genetic, but the degree of in creased risk is small.