Association between breast and colorectal cancer in a sample of surgical patients.

The frequency of adenomatous polyps and adenocarcinomas of the large bowel in 95 patients mastectomized for breast cancer, and the prevalence of breast cancer in 77 women previously operated on for colorectal cancer were evaluated by means of a case-control study. The mastectomized patients as well as the control group, underwent a left-sided colonoscopy. The latter had been selected among women spontaneously referring to our gastroenterological out-patients clinic. The choice of this self selected control group could produce a under-estimation of the relative for colon cancer in mastectomized patients. Among mastectomized patients the frequency of adenomatous polyps and colorectal cancer was 10.5% and 5.3% respectively; while the control group showed 8.5% frequency for adenomatous polyps and 3.9% frequency for cancer. These figures are not statistically different. Patients operated on for colorectal cancer and the control group underwent clinical and mammographic examination. The prevalence of breast cancer among colorectal cancer patients and the control group women was 5.2% and 0.3% respectively (10 times higher): the difference was statistically significant (P less than 0.006). In spite of the relatively small number of studied cases, our finding are consistent with the hypothesis of a correlation between breast cancer and colorectal cancer.