Cancer incidence among spouses of patients with colorectal cancer.

The risk of colorectal cancer was examined among spouses of approximately 10,000 colorectal cancer patients. A total of 8,095 spouses were identified, and cancer cases in this cohort were sought in the Danish Cancer Registry. No excess risk was found for colorectal cancer as such. The data were also analyzed by subsite of the large bowel for the index cases and for the spouses, respectively. The estimated relative risks were in general close to unity, the only exception being the risk of right-sided colon cancer among husbands of index cases with left-sided colon cancer, RR = 2.17 (p less than 0.05). The absence of excess risk was noted regardless of the duration of marriage. The risk of other cancers with a presumed etiology similar to that of colorectal cancer (cancer of the uterine corpus, breast, prostate and biliary tract) was also close to expected values.