Endoscopic resection has been limited to intestinal-type gastric cancer (cT1a) with a low risk of lymph node metastasis (T1a ≤2 cm, without ulcers). This single-arm confirmatory trial evaluated the efficacy and safety of endoscopic submucosal dissection (ESD) for >2 cm ulcer-negative and ≤3 cm ulcer-positive intestinal-type gastric cancer (cT1a).

The eligibility criteria included endoscopically diagnosed cT1a, a single primary intestinal-type gastric adenocarcinoma, an ulcer-negative lesion of any size or a ≤3 cm ulcer-positive lesion, cN0M0, and no prior treatment. If ESD resulted in noncurative resection, surgical resection was added. The primary endpoint was the 5-year overall survival (OS) (planned sample size was 470, with a one-sided alpha level of 2.5%). The threshold 5-year OS was 86.1%.

We enrolled 470 early gastric cancer patients [median tumor size, 25 (5–130) mm] from 29 institutions between June 2007 and October 2010. These patients had 152 ulcer-negative lesions (>2 and ≤3 cm), 111 ulcer-negative lesions (>3 cm), and 207 ulcer-positive lesions (≤3 cm). The success rate for en block resection was 99.1% (466/470). Additional gastrectomy was conducted in 131 patients (28%) who did not fulfill the curative resection criteria. The 5-year OS of all patients was 97.0% (95% confidence interval, 95.0–98.2%), which was higher than the threshold 5-year OS (86.1%). The 317 patients who satisfied the curative resection criteria had no recurrence. There were no ESD-related grade 4 adverse events.

ESD for early gastric cancers that met the expanded criteria for intestinal-type gastric cancer (cT1a) was acceptable and should be the standard treatment instead of gastrectomy.