Correlation between colon adenoma and cancer

In the course of 1301 colonoscopies performed by the authors, in cases of 127 patients (9.76%), 177 polyps were removed; 159 (89.83%) out of them proved to be adenomas by histology. In 23 adenomas (14.46%) malignant transformation was observed. The highest percentage of polyps was detected in the group of patients with tumours, and a somewhat lower proportion was found in the case of patients who underwent resection surgery because of tumours. A similar tendency could be seen concerning the malignant transformation of the removed adenomas. Our data seem to support the theory by Morson and Hermanek regarding the transformation from adenoma to cancer in the large bowel. Surgery is proposed in the following types of colon polyps: (1) polyps unremovable by endoscopic polypectomy, even by piecemal snare excision; (2) invasion (adenoma with invasive adenocarcinoma)--if the tumour is situated within a 3 mm distance from the resection line; (3) following endoscopic removal of polypoid adenocarcinoma (in this case the site of polypectomy can be marked by preoperative injection of ink or in the course of intraoperative colonoscopy); (4) in the case of complications of endoscopic polypectomy (perforation, bleeding uncontrollable by conservative or endoscopic means); (5) colotomy and polypectomy should be performed when the adenoma cannot be reached with the endoscope--for technical reasons--and the intraoperative method cannot be used under the conditions of an open abdomen but without the necessity of opening the bowel.