Heredity and colorectal cancer. A prospective, community-based, endoscopic study.

The frequency of colorectal neoplasia was assessed through colonoscopy in 114 patients with a family history of colorectal cancer. In over 90 percent of patients, a first-degree relative was affected. Twenty-one percent of patients who were studied endoscopically were positive for neoplastic disease, including two invasive cancers. Twenty-eight percent of patients had adenomas beyond the splenic flexure. Multiple primary relatives further increased risk with 36 percent positive for neoplasia. Neoplasia was common in young patients, with 25 percent under the age of 40 years positive for adenomas. These findings are identical to recent pedigree studies and further support a genetic basis for common colorectal cancers. First-degree relatives of patients with colorectal cancer should be considered at high-risk for colorectal neoplasia. Screening and surveillance with colonoscopy is recommended.