REGIONAL PROLIFERATIVE PATTERNS IN THE COLON OF PATIENTS AT RISK FOR HEREDITARY NONPOLYPOSIS COLORECTAL-CANCER

Patients from a hereditary nonpolyposis colorectal cancer (HNPCC) kind red (Lynch Type 1 and Type 2) have an increased risk of developing lar ge-bowel cancer. Tumors occur at a young age and are characteristicall y right-sided. Colonic mucosal proliferation is known to be increased in several groups of patients at risk of colorectal cancer. PURPOSE: T his study was performed to assess the pattern of mucosal proliferation at different sites in the colon of patients at risk of HNPCC and to d etermine whether this pattern differs from normal patients. METHODS: M ucosal biopsies were obtained at colonoscopy from 21 patients at risk for HNPCC (16 females; mean age, 42 years) and from 7 normal patients (4 females; mean age, 38 years), and mucosal proliferation was quantif ied using the whole crypt mitotic count (WCMC) technique. RESULTS: In patients from HNPCC families, WCMC and crypt area were significantly g reater in the cecum than in the transverse colon and left colon (P < 0 .001). Compared with normal patients. WCMC in HNPCC patients was signi ficantly greater in the cecum only (P < 0.05). A significant right-to- left shift was also observed in normal patients, but the percentage in crease from right to left was two-fold greater in HNPCC patients. CONC LUSIONS: These results confirm a proximalto-distal proliferative gradi ent in the human colon and suggest that this may be exaggerated in HNP CC. This increased proximal proliferative rate may be a factor in the development of right-sided cancer in these patients.