Background and study aims: It is difficult to measure the prevalence of hereditary non-polyposis colorectal cancer (HNPCC) in geographical areas that do not have tumor registers, as is the case in the present study, and it was therefore decided to assess the prevalence in Italy using different methods.
Patients and methods: The pedigree was established for 485 of 501 colorectal cancer patients diagnosed with colorectal carcinomas. Patients were included consecutively in 13 gastroenterology centers; they had not taken part in prevention examinations. Information was collected regarding the neoplastic pathology observed in the families, confirmed in 90% of cases among 3515 first-degree relatives and in 79.5% of cases among 7068 second-degree relatives.
Results: In the 3515 first-degree relatives (1002 parents, 1560 siblings and 953 children), 61 colorectal carcinomas, 29 carcinomas in the digestive tract outside the colon, and 99 carcinomas in other locations were reported. Only five of the 485 patients (1%) satisfied the Amsterdam criteria (three cancers, two of which were in first-degree relatives in different generations and one in a relative younger than 50). When broadening the criteria that we are proposing (satisfying only two of the three Amsterdam criteria), the prevalence would increase to 3% (15 cases).
Conclusions: Modifying the criteria makes it easier to identify new mutations or confirm the existence of those already known, as well as allowing preventative treatment in relatives who are apparently healthy.