Colonic neoplasms in asymptomatic first-degree relatives of colon cancer patients.

First-degree relatives of colon cancer patients are at elevated risk for developing colorectal neoplasms. In order to assess the potential usefulness of screening by colonoscopy in this high-risk population, we reviewed the records of 48 colonoscopies performed on asymptomatic patients who were self- or physician-referred for colonoscopy because of a history of one or more first-degree relatives with colon cancer. Twelve (25%) had at least one adenomatous polyp, but no significant atypia was detected. No cancers were detected. One third of the lesions were beyond the reach of a flexible sigmoidoscope. This apparent increase in the prevalence of adenomas was most striking (46%) among men over the age of 50. These preliminary results demonstrate that colonoscopy is effective in detecting and removing adenomatous polyps in a substantial fraction of asymptomatic patients whose sole risk-factor is being a first-degree relative of a patient with colon cancer. Further studies in larger populations are warranted to determine the use of colonoscopy in screening these high-risk individuals.