확대적응증. EndoTODAY 이준행

Gut and Liver 지의 Editorial을 통하여 expanded indication에 대한 입장을 밝혔습니다.(2015)

First of all, a standard definition of EI is urgently needed. By the recently published clinical practice guideline for gastric cancer in Korea, expanded indications include (1) well or moderately differentiated adenocarcinoma in the mucosal layer without an ulcer regardless of the size, (2) well or moderately differentiated adenocarcinoma measuring less than 3 cm in the mucosal layer with ulcer, (3) small (less than 2 cm) intramucosal cancer with undifferentiated histology, and (4) well or moderately differentiated adenocarcinoma with minute submucosal invasion (500 or less micrometer, SM1).¹ However, there is no consensus whether undifferentiated type EGCs (i.e., poorly differentiated adenocarcinomas and signet-ring cell carcinomas) should be included in EI of ESD. Data on clinical outcomes of ESD for undifferentiated type EGCs indicate that optimal curative resection would be difficult to guarantee, given the overall unpredictability of tumor depth and extent. In addition, there is little long-term outcome data to support endoscopic treatment of undifferentiated type EGC at this time.^2-4 There are some cases with histological heterogeneity. In order to avoid confusions regarding histological type, we propose that the long-term outcome of ESD for differentiated type EGCs, undifferentiated type EGCs, and EGCs with mixed histology need to be separately reported.

The second limitation can be named as 'indication/criteria issue'. We choose ESD candidates using some kind of indications. After ESD, we evaluate the resected specimen using some kind of criteria. The contents of indications and criteria may be the same. However, indications are something before ESD, and criteria are something after ESD. The ‘indication/criteria issue’ is related with the problem of pre- and post-resection diagnostic discrepancies. Recent clinical analysis from Samsung Medical Center has shown that about one third of pre-resection AI-EGC was shifted to post-resection beyond AI-EGC, and 42.8% of the changes were beyond EI for ESD.⁵ Another report from National Cancer Center demonstrated that 13.7% were out-of-indication at the pathological evaluation of resected specimen in pre-resection AI group, and 35.3% were post-resection out-of-indication in the clinically EI group.⁶ Until now, most data on ESD for EI-EGC are based on post-resection diagnostic groups. This means a lot of cases in reports on ESD for EI-EGC were originally considered as AI-EGCs before ESD. If we do not consider this bias carefully, patients can be exposed to unnecessary risks.

Long-term follow-up data likewise are generally troublesome. According to various observational cohort studies, outcomes of ESD in EGC were similar whether AI or EI were applied.^7-9 Neither overall nor disease-free survival rates routinely differed in groups classified by indications. On the other hand, most investigations have clearly been plagued by less than adequate durations of follow-up. Although some 5-year follow-up data have been analyzed, yielding little survival differences between groups, evidence supporting favorable long-term oncologic outcomes is meager. Furthermore, greater care should be devoted to subject selection, inasmuch as most patients of EI groups were surgically treated as well. Prospective randomized clinical trials for EI-EGCs are strongly required for the definitive comparison between ESD and surgery.

1. Lee JH, Kim JG, Jung HK, et al. Clinical practice guidelines for gastric cancer in Korea: an evidence-based approach. J Gastric Cancer 2014;14:87-104.
2. Okada K, Fujisaki J, Yoshida T, et al. Long-term outcomes of endoscopic submucosal dissection for undifferentiated-type early gastric cancer. Endoscopy 2012;44:122-7.
3. Kim YY, Jeon SW, Kim J, et al. Endoscopic submucosal dissection for early gastric cancer with undifferentiated histology: could we extend the criteria beyond? Surg Endosc 2013;27:4656-62.
4. Kim JH, Kim YH, Jung da H, et al. Follow-up outcomes of endoscopic resection for early gastric cancer with undifferentiated histology. Surg Endosc 2014;28:2627-33.
5. Lee JH, Lee JH, Kim ER, Kang KJ, Min BH, Kim JJ. Discrepancy between pretreatment and posttreatment diagnosis of early gastric cancer and its impact on treatment choice. 63rd Congress of the Korean Society of Gastrointestinal Endoscopy; 2013 Dec 23; Sheraton Grande Wolkerhill Hotel. Seoul: Korean Society of Gastrointestinal Endoscopy; 2013:78.
6. Kim HS, Kim YI, Lee JY, Kim CG, Kook MC, Choi IJ. Discrepancy between clinical evaluation and final pathological findings in early gastric cancer treated by ESD. 23rd Congress of the Helicobacter and Upper Gastrointestinal Research; 2014 Dec 14; Conrad Hotel. Seoul: Korean College of Helicobacter and Upper Gastrointestinal Research; 2014: 33.
7. Isomoto H, Shikuwa S, Yamaguchi N, et al. Endoscopic submucosal dissection for early gastric cancer: a large-scale feasibility study. Gut 2009;58:331-6.
8. Lee H, Yun WK, Min BH, et al. A feasibility study on the expanded indication for endoscopic submucosal dissection of early gastric cancer. Surg Endosc 2011;25:1985-93.
9. Park CH, Shin S, Park JC, et al. Long-term outcome of early gastric cancer after endoscopic submucosal dissection: expanded indication is comparable to absolute indication. Dig Liver Dis 2013;45:651-6.