The incidence and prevalence of familial polyposis coli in Denmark.

Based on the Danish Polyposis Register, the frequency of familial polyposis coli was estimated at the end of 1982. The mean annual incidence rate of polyposis coli has remained rather constant at approximately 1 X 10(-6) X yr-1 since the forties. The life-time risk of developing polyposis coli is about 1 X 10(-4). The point prevalence rate was 26 X 10(-6) at the end of 1982. The number of cases found in sibs and children of probands made it probable that a nation-wide prophylactic examination of first degree relatives resulted in a complete identification of affected family members. The completeness of the Danish Polyposis Register in the period 1976-82 was estimated to be 90% and the validity of the diagnosis is considered to be 100%.