The detection of aberrant DNA synthesis in a member of a high-risk cancer family.

Relatives of patients with multiple polyposis are among those at high risk for development of neoplasms in the colon. Examination of 4 siblings, 3 men and 1 woman, of a patient with multiple polyposis was conducted for the possible presence of colonic polyps. All patients were over 40 years of age and received barium enemas for the radiological detection of excrescences. Proctoscopic examinations were also carried out during which time a biopsy and colonic wash were obtained. Polyps were absent on films as well as on endoscopy, and colonic cytologies of all 4 subjects were within normal limits. However, isotopic incorporation studies revealed the presence of an abnormal labeling pattern in some crypts of the biopsy incubated with TdR-3H of 1 family member. Along with normal crypts with label in the lower two-thirds of the colonic crypts, some were seen to have cells labeled at the surface, a proliferative lesion thought to precede the apperarance of a polyp. Among the surface cells removed by the colonic wash, some were found to be isotopically labeled, that is, engaged in DNA synthesis. Thus, a defect in the regulation of colonic epithelial cell replication was found, suggesting the need for close surveillance in the interest of early colon cancer detection.