A clinicopathological investigation on superficial early invasive carcinomas of the colon and rectum.

Due to recent advances in endoscopic surgical techniques, it has now become possible to perform endoscopic resection of most early invasive carcinomas of the colon and rectum (EIC) even if the lesions have invaded the submucosa. In the present study, we investigated the microscopic characteristics of superficial EIC compared with protruding-type EIC, focusing particular attention on histological type, the presence or absence of vascular invasion, the extent of submucosal invasion, and other adverse prognostic factors, to establish appropriate treatment strategies. Our findings led us to conclude that: (1) most cases of EIC can be cured by endoscopic resection if their gross aspects are classified as type IIc, superficial depressed, or type IIa, superficial elevated; (2) colorectal resection with lymph node dissection should be performed first for type IIa + IIc EIC because these lesions are apt to be associated with a large number of adverse prognostic factors; (3) subsequent colorectal resection should be performed after initial endoscopic treatment of EIC if there are adverse prognostic indicators of metastasis in the endoscopically resected specimen, such as moderately or poorly differentiated adenocarcinoma, lymphatic invasion, venous invasion, or extensive submucosal invasion.