This multi-center, randomized controlled trial is designed to evaluate clinical effectiveness and cost-effectiveness of ESD for undifferentiated type of EGC meeting the expanded indication compared with surgery.

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.

Inclusion Criteria:

1. Patients who are diagnosed with undifferentiated type EGC (signet ring cell carcinoma, poorly differentiated tubular adenocarcinoma, or poorly cohesive carcinoma) that meets the expanded indication of ESD 1) Tumor confined to the mucosa without ulcer, and size ≤2 cm on endoscopic evaluations 2) No evidence of lymph node metastasis and distant metastasis on abdominal CT scan
2. Adult patients aged 19-75 years
3. Patients who had willingness to sign an informed consent form

Exclusion Criteria:

1. Patient age: < 19 years or age > 75 years
2. Diagnosis and active treatment for other organ cancer except carcinoma in situ and non-melanomatous skin cancer within 5 years
3. Previous gastrectomy or esophagectomy history
4. Multiple gastric cancers
5. Current treatment for serious medical condition which could hinder study participation including severe heart dysfunction, liver cirrhosis, renal failure, chronic obstructive pulmonary disease or asthma, or uncontrolled infection
6. Inability to provide an informed consent
7. Inadequate conditions for study enrollment according to the evaluation of study physicians