TUMOR SPECTRUM IN HEREDITARY NONPOLYPOSIS COLORECTAL-CANCER (HNPCC) AND IN FAMILIES WITH SUSPECTED HNPCC - A POPULATION-BASED STUDY IN NORTHERN ITALY

Hereditary non-polyposis colorectal cancer (HNPCC or Lynch syndrome) i s characterized by the early onset of colorectal neoplasms, frequently localized in the right colon, increased occurrence of multiple primar ies, vertical transmission and aggregation of tumours in families in a ccordance to a Mendelian dominant type of inheritance. The syndrome ac counts for approximately 5% of all colorectal cancers. The purpose of the present study was to describe the tumour spectrum and the most rel evant clinical features of 28 kindreds with HNPCC, classified accordin g to the guidelines of the international Collaborative Study Group, an d of 61 ''suspected'' HNPCC. These families were observed during a 6-y ear registration of colorectal neoplasms in a health-care district of Northern Italy. Colorectal cancer was by far the most frequent maligna ncy; gastric cancer was the second. Uterine carcinoma was only slightl y more frequent than expected. Lung- and breast-tumour rates were lowe r than expected. Cancer distribution in the large bowel showed that ab out two fifths of the tumours developed in the right colon. The occurr ence of cancer before the age of SO to 60 was much more frequent in HN PCC. Multiple tumours developed in 25 patients with HNPCC and in 32 wi th ''suspected'' HNPCC. Pancolonoscopy remains the procedure of choice for surveillance; other examinations, such as gastroscopy, gynaecolog ical investigations, urography and cholangiography, are suggested only to selected families. One of the main features of the study was the i nclusion of 61 ''suspected'' HNPCC, a heterogeneous group of families which nonetheless deserves careful follow-up.