Comparative histologic study of adenomas of the large intestine in Japan and England, with special reference to malignant potential.

The malignant potential of large-intestinal adenomas varies with size, histologic type, and grade of epithelial atypia in the same way in England and in Japan. Adenomas in England have greater malignant potential than those in Japan because they grow larger and more often show a villous growth pattern. Although the adenoma--carcinoma sequence operates in the same way in the two countries it is suggested that the higher incidence of colorectal cancer in England is due to the greater prevalence as well as the greater size of English adenomas. More studies of the epidemiology and geographic pathology of large-intestinal adenomas are needed to clarify their importance as a predisposing cause of colorectal cancer in low-risk as well as high-risk areas.