[Familial incidence of colorectal carcinoma and its significance for a screening program (the example of Upper Basel area)].

Primary prevention of colorectal carcinoma aims at interruption of the adenoma-carcinoma sequence. Colonoscopy is the most reliable screening method, but up to now has only been recommended for persons at high risk. The ongoing 10-year study defines a possible risk group and determines the efficacy of a preventive screening program based on family history. This paper reports on the descriptive statistics of the first five years. All patients with colonic carcinoma diagnosed between 1987 and 1991 living in the upper part of Canton Basel-Land were registered. According to the family history, patients with at least one first degree relative with colonic carcinoma were defined as index patients. Their first degree relatives entered a prospective screening program which includes colonoscopy. 230 colonic carcinomas were diagnosed in the upper part of Basel-Land, representing an incidence of 48/year/100,000 persons. They included 3 (1.3%) hereditary and 227 (98.7%) sporadic carcinomas. 23 (10%) patients had a positive family history. These patients defined 94 relatives at risk. The incidence of colonic carcinoma in the Canton studied does not differ from that reported in Switzerland. Therefore, this part of Basel-Land can be considered representative. The 1.3% hereditary carcinomas are in contrast to the published data of 6%.