| Since recent advancement of endoscopic therapeutic technology, the numbers of endoscopic resection for early colorectal carcinomas with little risk of lymph node metastasis is increasing. There have been no reports of lymph node metastasis in intramucosal (Tis) carcinomas, while lymph node metastasis occurs in 6.8-17.8 % of submucosal (T1) carcinomas. Three clinical guidelines have been published in Japan and the strategy of the management for early colorectal tumors is demonstrated. According to 2016 JSCCR Guidelines for the Treatment of Colorectal Cancer, among endoscopically treated carcinomas, T1 carcinoma with a histologically diagnosed as a positive vertical margin should be performed additional surgery. Additional surgery may be considered when at least one of the following histological findings is detected: i) SM invasion depth >=1,000μm; ii) histological type of por., sig., or muc.; iii) budding grade2-3; and iv) positive vascular permeation. While resected lesion is histologically diagnosed as a T1 carcinoma without any histological findings mentioned above, it could be followed up without additional surgery. In order to accomplish complete endoscopic resection with both vertical and horizontal margin negative, ESD is a reliable technique for en block resection regardless of lesions size compared with conventional EMR. Piecemeal conventional EMR or cold snare polypectomy are not suitable for complete resection of T1 carcinomas because of difficulty of precise histological diagnosis as we reported before (Am J Gastroenterol. 2015). It has been discussed about the possibility of the endoscopic total excisional biopsy for T1b carcinomas (T1 carcinoma with >=1,000μm SM invasion depth) using JNET magnifying NBI classification (GIE. 2016) or EUS (Int J colorectal dis. 2013). As for the prognosis of endoscopically resected T1 carcinomas, relapse ratio is relatively low as about 3.4%(44/1,312), but prognosis was poor as 72 of cancer death out of 134 relapsed cases (54%) once relapse has occurred. It is expected that more detailed stratification of lymph node metastasis risk after endoscopic resection for T1 carcinomas and the prognosis of relapsed cases in a prospective fashion will become apparent, and appropriate indication of endoscopic resection including total incision biopsy for T1 carcinomas will be established. |
