Colorectal adenomas and cancer: pathologic relationships.

The relationship of adenomatous polyps and hyperplastic polyps to carcinomas of the colon and rectum are discussed. There is a continuum of neoplastic alterations from adenomas to invasive carcinomas, which is defined. Clinically relevant prognostic factors in adenomas containing cancer are evaluated. Degree of differentiation, depth of invasion, and the relative amount of carcinoma are important factors.