|Colorectal cancer (CRC) is one of the most common cancers worldwide. The incidence of CRC has rapidly increased in recent decades in many Asian countries. In Korea, CRC is the third most common cancer in both sexes. Increasing implementation of screening has led to an increase in the proportion of early stage cancers. Endoscopic resection of intramucosal carcinomas is considered to be a curative therapy because there is little risk of lymph node metastasis (LNM). However, invasive CRCs confined to the colonic submucosa (T1 CRC) represent a challenging category with regard to treatment decisions, because LMN occurs in approximately 6% to 12% of patients with T1 CRC. According to the 2014 Japanese Society for Cancer of the Colon and Rectum (JSCCR) Guidelines, T1 CRC, that are histologically diagnosed with negative vertical margins, favorable histological grade (papillary adenocarcinoma or tubular adenocarcinoma with submucosal invasion depth (< 1000 µm), without vascular or lymphatic invasion and with grade 1 tumor budding, is considered to be low-risk for LNM and can be followed up without additional surgery. Endoscopic resection is commonly carried out for these low-risk T1 CRCs based in these guidelines. In addition, improvement of endoscopic submucosal dissection has made possible en bloc resection of T1 CRCs, which enhances pathologically complete resection.
Recent Japanese studies have reported that long-term outcomes of T1 CRCs after endoscopic or surgical resection supported the JSCCR 2014 criteria for endoscopically curable T1 CRC, and endoscopic resection did not worsen the clinical outcomes of patients who required additional surgery. The long-term outcomes of endoscopic treatment compared to surgery are not well established in Korea. Recent study from National Cancer Center in Korea analyzed 430 patients with T1 CRC who underwent local or surgical resection, and reported that disease recurred in 16 (3.7%) patients in the high-risk group, and no recurrence in the low-risk group. Local resection and positive vascular invasion for patients with high-risk group were significantly associated with poor 5-yeat disease-free survival and overall survival. Another study from Yonsei University Hospital showed that endoscopic treatment was associated with favorable long-term outcomes compared to surgery for initial treatment of patients with low-risk T1 CRC. Taken together, endoscopic resection may be effective and oncologically safe in low-risk T1 CRC. In this talk, I present results of our hospital for the long-term outcomes of T1 CRC after endoscopic or surgical resection and risk factors associated with LNM or recurrence.