THE ROLE OF COLONOSCOPY IN SCREENING PERSONS WITH FAMILY HISTORY OF COLORECTAL-CANCER

First-degree relatives of colorectal cancer patients are at increased risk for developing colorectal neoplasms. In order to assess the poten tiality of colonoscopy screening in this high-risk population, 213 asy mptomatic family members (age range 30-69 years, mean 42.8 years) of t hose patients with colorectal cancer received colonoscopic examination at Chang-Gung Memorial Hospital from April 1992 to May 1994. Twenty-e ight persons with 42 lesions (polyps or cancer) were identified, inclu ding 28 adenomas, nine hyperplastic polyps and five adenocarcinomas. T he positive detection rate was 9.9% for adenoma and 2.3% for cancer. C olorectal neoplasms afflicted males more frequently than females (16.7 vs 5.7%, P < 0.05) and occurred less frequently in those < 40 years o f age (5.5 vs 17.2%, P < 0.05). Forty-two per cent of the detected neo plastic lesions were beyond the reach of 60 cm flexible sigmoidoscopy and 36% of adenomas were < 0.5 cm in size and would be missed if patie nts were screened by air contrast barium enema. Cost analysis revealed that the charges of both screening colonoscopy and screening flexible sigmoidoscopy/air contrast barium enema were approximate. Colonoscopy also has a high acceptability and safety. It appears appropriate to u se colonoscopy, rather than flexible sigmoidoscopy or air contrast bar ium enema, as an initial screening procedure for persons with a family history of colorectal cancer, especially those > 40 years of age.