Exploring the Evidence of Expanded Criteria for Endoscopic Resection of Early Gastric Cancers

Traditionally, gastrectomy with lymph node dissection is recommended as a curative treatment modality. In Korea, gastric cancer screening is covered by the Health Insurance System for individuals aged 40 years or older; therefore, gastric cancer is now detected in its early stages. Minimally invasive treatment using endoscopic resection is indicated for early gastric cancer with a low risk of lymph node metastasis. As proposed by the Japanese Gastric Cancer Association, endoscopic resection is now the accepted standard treatment if the gastric cancer fulfills the following absolute criteria: ≤2 cm tumor size, intramucosal, differentiated histological type of cancer, and absence of ulceration. Current guidelines suggest that the criteria can be broadened to include larger lesions (>3 cm), ulcerative lesions of relatively small size (≤3 cm), superficial submucosal invasive cancer (≤ 500 μm) ≤3 cm in size, or undifferentiated cancer within 2 cm in size if other conditions are compatible with the absolute criteria. The current guidelines define the expanded indication for endoscopic submucosal dissection (ESD) as an investigational treatment because the existing evidence is still insufficient for its use as a curative treatment modality. Two possible approaches can be used to prove the acceptability of an expanded indication. The first is to show that the long-term survival rates in the expanded indication are comparable with those of the absolute indication, in which ESD is a standard treatment. Several large-series retrospective studies have shown that long-term outcomes of the two indications were quite similar and excellent. The second approach is to prove that the outcomes of the expanded indication are comparable or better than those of the standard surgical treatment (i.e., gastrectomy with lymph node dissection). Prospective randomized trial will be the best study design but is virtually impossible to perform. Therefore, an approach that uses retrospective comparative analyses might provide an acceptable option. In this issue of Clinical Endoscopy, Shin et al. reported a confirmative study showing that long-term survival after ESD was not significantly different from that after gastrectomy. The study analyzed 275 propensity score-matched patients with a median follow-up duration of 56 months and showed that the 5-year overall survival rate was 92.0% in the ESD group and 93.3% in the gastrectomy group. Moreover, the complication rates were much lower after ESD (5.1%) than after gastrectomy (15.0%). The reported results were similar to those of recent studies that showed a comparable long-term outcome of ESD in terms of overall survival rate with that of surgery, including lower complication rates. The length of hospital stay and the treatment costs in ESD treatment were superior to those in surgery for early gastric cancer within the expanded indication, as previously reported. When interpreting the results of this study, several limitations should be emphasized. First, the study suggested a Received: March 11, 2017 Revised: March 21, 2017 Accepted: March 21, 2017 Correspondence: Il Ju Choi Department of Gastroenterology, Center for Gastric Cancer, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang 10408, Korea Tel: +82-31-920-2282, Fax: +82-31-920-0069, E-mail: cij1224@ncc.re. kr