[Debatable and unclear questions concerning the morphogenesis of cancer of the large intestine and rectum].

The analysis of the pertinent literature shows that there is no reliable evidence on the essential importance of intestinal adenomatous polyps in carcinogenesis. The villous and glandular-villous tumours very often are considered to be highly malignant. However the growth pattern as well as histological, iltrastructural, histochemical, immunological, and other characteristics of villous tumours are close to those of adenocarcinomas. Therefore, villous tumours without invasion can be referred to as either carcinoma in situ of superficial cancer. The combination of experimental investigations and studies on human material indicates that colonic cancer prodeminantly develops de novo, that is, without preceeding morphological changes.