| [ Summary ] |
637 small invasive cancers of the colon and rectum (less than 10 mm) were examined at 16 special hospitals in Japan. Employing endoscopic examinations, small invasive cancers were divided into 3 groups, protruded type (Is, Isp, Ip), flat type (IIa, LST) and depressed type (IIc, IIc + IIa, IIa + IIc, Is + IIc). Depth of tumor invasion was measured in relation to absolute values from the lamina muscularis mucosae. The lesions were from 637 patients (456 men, 181 women ; mean age, 63.4 years). There were 168 tumors (26.4 %) located from the cecum to the transverse colon. There were 328 lesions (51.5 %) located from the descending colon to the sigmoid colon. 141 lesions (22.1 %) were located in the rectum. There were 285 lesions (44.7 %) of the protruded type, 98 lesions (15.4 %) of the flat type and 254 lesions (39.9 %) of the depressed type, which were observed endoscopically. 207 lesions (32.5 %) tested positive for vascular invasion through pathological examination. There were 33 cases of lymph node metastasis (9.6 %) out of 345 surgical cases. Of the 33 cases, 25 (75.8 %) were located from the sigmoid colon to the rectum, and 19 (57.6 %) were of the depressed type. |