Results of national registration of familial adenomatous polyposis

Background and aims: The Danish Polyposis Register was established in 1971 with the aim of improving the poor prognosis of familial adenomatous polyposis (FAP), and in 1975 the register became national. The aim of the present study was to evaluate the prevalence of colorectal cancer and survival rate in FAP patients before and after the establishment of the Danish Polyposis Register. Patients and methods: The Danish Polyposis Register was established by collecting information on probands and construction of their pedigrees. Family members at risk were offered prophylactic endoscopic and molecular genetic examination, and affected individuals were treated by colectomy. Results: At the end of 2001, the Danish Polyposis Register included 434 patients from 165 families. The incidence rate was 1.90x10(-6) and the prevalence rate 4.65x10(-5). Colorectal cancer on the basis of FAP constituted 0.07% of all colorectal cancers in the 1990s. Colorectal cancer was diagnosed in 170/252 probands (67%) and in 5/182 call-up patients (3%) (p<0.001). The cumulative crude survival was 94% in call-up patients compared with 44% in probands (p<0.0001). A comparison of two periods, 1900-1975 and 1976-2001, demonstrated a decreased prevalence of colorectal cancer from 60% to 27% (p<0.0001), and an increased use of colectomy from 52% to 93% (p<0.00001). The cumulative crude survival in FAP showed substantial improvement with time (p<0.00001). Conclusion: Since the establishment of the Danish Polyposis Register, the prevalence of colorectal cancer has decreased considerably and the prognosis has improved substantially. The work of the Danish Polyposis Register is probably the main cause of this improvement.