Purpose: Identification of the hereditary non-polyposis colorectal carcinoma syndrome (HNPCC) is a basis for secondary prevention. The objectives of this study are to investigate the natural history of HNPCC and to assess the effect of screening.
Patients and methods: Screening for colorectal carcinoma was performed in 22 HNPCC families (colonoscopy or double-contrast barium enema and sigmoidoscopy). The patients were subdivided into two groups. Group A comprised patients with colorectal cancer who were referred because they were symptomatic. Group B included family members of these patients who were found to have a colorectal lesion by screening. We compared these groups with respect to the stage of tumor growth.
Results: Histologic examination of the tumors in Group A (87 patients) revealed Dukes A carcinomas in six patients, Dukes B carcinomas in 37, Dukes C carcinomas in 21, and Dukes D carcinomas in 10 patients (classification unknown in 13 patients). In Group B (20 patients), adenoma was found in 14 and carcinoma in six patients (Dukes A in two and Dukes B in four patients). A total of 93 patients, including those whose tumors were detected by screening, had a colorectal carcinoma. The age at diagnosis ranged from 24 to 81 years (mean age: 46 years). The location of the colonic tumors was proximal in 60 percent. Multiple primary tumors were found in 26 percent.
Conclusion: These results suggest that screening leads to the early detection of colorectal carcinomas and adenomas in asymptomatic members of HNPCC families. Screening should be initiated at the age of 20 and continued during the life of the individual. Careful examination of the right colon is indicated because of the frequent occurrence of tumors in the proximal colon. A subtotal colectomy is indicated at the time of diagnosis of the initial colon cancer because of the risk of multiple primary tumors.