Adenomas are precursor lesions for malignant growth in nonpolyposis hereditary carcinoma of the colon and rectum.

The relationship of adenoma to carcinoma of the colon and rectum in individuals of families with nonpolyposis hereditary carcinoma of the colon and rectum syndrome is uncertain. In five families with hereditary carcinoma of the colon and rectum, the medical records of 39 patients who had 50 instances of carcinoma of the colon and rectum develop were studied. Six instances of disease were found in adenomas: Dukes' A in two; Dukes' B in three, and Dukes' C in one. The malignant polyp was the only neoplastic lesion in the colon in five of these instances. In only 12 of the patients (31 per cent) were adenomas (seven patients) or secondary disease (five patients) ever found. These data suggest that while uncommon adenomas are precursor lesions for malignant neoplasms in patients with carcinoma of the colon and hereditary carcinoma of the colon and rectum syndrome.