Comparison of Endoscopic Resection and Surgery for Early Gastric Cancer With Undifferentiated Histological Type

Endoscopic submucosal dissection (ESD) is a minimally invasive treatment of early gastric cancer (EGC). Because of the stomach preservation, ESD provides a better quality of life (QoL) in EGC patients than surgery. In addition, medical costs are lower in patients underwent ESD than in those underwent surgery. In 2018, gastric cancer management guidelines by the Korean Gastric Cancer Association and Japanese Gastric Cancer Association (JGCA) stated that undifferentiated type of EGC, clinically diagnosed as tumor confined to the mucosa without ulcer, and size ≤2 cm, is included in the expanded indication of ESD. In the 2018 JGCA guideline (version 5), ESD is an investigational treatment for patients with undifferentiated type of EGC meeting the expanded indication whereas surgery (gastrectomy with lymph node dissection) is a standard treatment. Previous single center retrospective studies reported favorable long-term outcomes of ESD for undifferentiated type EGC meeting the expanded criteria on final pathological evaluations compared with that of surgery. More recently, a multi-center retrospective cohort study including 18 Korean university hospitals also reported no significant difference in overall mortality between ESD and surgery after propensity score matching (hazard ratio \[HR\] for overall mortality in the ESD group, 2.36; 95% confidence interval \[CI\] 0.91-6.10; p=0.078) during a median follow-up of 75.6 months. However, gastric cancer recurrence occurred only in the ESD group, and the HR for gastric cancer recurrence in the ESD group was 25.49 (95% CI 1.32-491.27; p=0.032). The 3-year disease-free survival (DFS) rate including gastric cancer recurrence or death was 94.9% in the ESD group and 98.1% in the surgery group. Thus, surgery group had a better DFS than ESD group (p=0.002 by log-rank test), and the HR for gastric cancer recurrence or death in the surgery group compared with the ESD group was 0.26 (95% CI, 0.10-0.64; p=0.003). However, previous studies could provide only a low level of evidence because of study limitations including the retrospective study design and incomplete data of patient survival and gastric cancer recurrence during follow-up. The studies did not evaluate QoL and cost-effectiveness after ESD and surgery. Therefore, we designed a multi-center, randomized controlled trial to provide a high level of evidence for clinical effectiveness and cost-effectiveness of ESD for undifferentiated type of EGC meeting the expanded indication.

• 3-year disease-free survival in the PP population [Time frame: 3 years after the last participant enrollment]
• Overall survival [Time frame: 5 years after the last participant enrollment]
• Curative resection rate of ESD [Time frame: 2 year after the participant enrollment]
• Quality of life changes during follow-up periods [Time frame: 3 years after the last participant enrollment]
• Treatment related complications (adverse events) [Time frame: 3 years after the last participant enrollment]
• Cost-effectiveness measured with Incremental cost effective ratio (ICER) [Time frame: 3 years after the last participant enrollment]