A Case-Control Study on Familial Aggregation of Colorectal Cancer

A Case-control study was conducted in 110 patients with colorectal cancer and, as control groups, 84 with gastric cancer, 50 with other cancer and 111 with benign gastroenterological disease. In this study we try to make it clear whether colorectal cancer has really familial aggregation and whether a positive family history can be used as one of screening procedures, by getting information more exactly about family history and by taking account of family size into analysis. 9.1% (OR 1.20) of colorectal cancer group and 11.3% (OR 1.70) of colon cancer group had positive family history of colorectal cancer, as compared with the benign disease group. 1.8% of their first-degree relatives were affected by colorectal cancer. No significant difference was seen, although these proportions were higher than those in 3 control groups. These results suggest familial aggregation of colorectal cancer is not so large as reseachers have mentioned so far, although a tendency for familial aggregation was found in colon cancer. At the present stage in Japan, we should not perform screening for the first-degree relatives only by positive family history from the reason of efficiency, though those of patients with clinically diagnosed or suspected HNPCC should be screened. J Epidemiol, 1995; 5 : 165-169.