Endoscopic screening of relatives of patients with colorectal cancer.

BACKGROUND The risk of colorectal cancer is higher among relatives of those affected. The neoplastic yield reported from screening such individuals varies enormously between studies and depends on the age and strength of the family history of those screened. AIMS To ascertain the neoplastic yield of endoscopic screening of first degree relatives of patients with colorectal cancer by age and familial risk. SUBJECTS A total of 330 individuals with a family history of colorectal cancer. METHOD Endoscopic screening conducted according to a protocol. RESULTS Adenomas were found in 12%, and adenomas larger than 1 cm in 8%, of "high risk" individuals screened primarily by colonoscopy. Of those with neoplasia, 26% had lesions at or proximal to the splenic flexure. Neoplasia was found in 9.5% of individuals at lower familial risk, screened primarily by 60 cm flexible sigmoidoscopy, 4% of whom had neoplasia larger than 1 cm in size or cancer. Neoplastic yield was greatest in the fourth and fifth decades in those at highest risk, but increased with age in those at lower risk. CONCLUSIONS For individuals with two or more first degree relatives, or relatives who have developed colorectal cancer at a young age, colonoscopy appears to be the only satisfactory method of screening, but 60 cm flexible sigmoidoscopy may be useful in those at lower levels of risk.