Background and aim:
Small (≤ 10mm) gastric submucosal tumors (SMTs) are common clinical findings. Although a watchful waiting approach is commonly adopted, patients are subjected to potentially decades of surveillance. Endoscopic resection has emerged as a promising alternative to enable early resection, but data comparing various methods is lacking. In this study, we first retrospectively reviewed and compared two cohorts of small gastric SMTs removed by cap-assisted endoscopic mucosal resection (C-EMR) and endoscopic submucosal dissection (ESD). A prospective randomized controlled trial (RCT) was then conducted to further validate the risk and safety of C-EMR and ESD as a primary treatment of small gastric SMTs.

Methods:
In the retrospective study, 93 patients who underwent C-EMR and 81 patients who underwent ESD as resection of small gastric SMTs in the Nanfang Hospital Southern Medical University, Guangzhou were reviewed. In the prospective RCT, 102 patients with small gastric SMTs were randomized to undergo C-EMR and ESD in a 1:1 ratio. Clinicopathological data and adverse events such as resection time, en-bloc resection rate, full thickness resection rate, and post-operative complications were compared.

Results:
In the prospective RCT, 102 small gastric SMTs with average tumor size 8.70± 0.15mm (C-EMR vs ESD: 8.89± 0.18mm vs. 8.51± 0.25mm, p=0.218) were successfully resected. Most of the SMTs were GISTs and leiomyomas (54.9% GIST, 36.3% leiomyoma, 1% Schwannoma, 1% calcifying fibrous tumor, 5.8% fusicellular tumor). The en-bloc resection rate was 96.1% (49/51) in both of the C-EMR group and of the ESD group. The rate of full thickness resection (EFTR) in the C-EMR group was similar to the ESD group [C-EMR vs. ESD: 51.0% (26/51) vs. 45.1% (23/51), p = 0.552]. The resection time (C-EMR vs ESD: 12.43±0.82 vs 22.20±1.45 min), the number of endoclips used (C-EMR vs. ESD: 5.96±0.21 vs. 7.53±0.41), and the average operation cost were significantly lower in the patients receiving C-EMR than those who underwent ESD (P<0.01). No significant difference was observed in the intraoperative complications as well as antibiotics or nasogastric tube usage, post-operative stay, and time to first liquid diet (p > 0.05). There were no post-operative complications such as delayed bleeding, perforation and peritonitis in both groups. Endoscopic follow-up after 3 months revealed healed wounds with no recurrence in all cases. In the retrospective study, a similar finding was noted.

Conclusion:
This study suggests that both C-EMR and ESD are safe and effective for small gastric SMTs and are reasonable approaches as primary treatment. Comparing the two endoscopic resection methods, there were significant advantages in the C-EMR in terms of shorter operation time, faster postoperative recovery, and lower operation cost. Further larger scale studies are indicated.

Image. Illustration of C-EMR and ESD for treatment of small gastric submucosal tumors

TABLE. Comparison of primary outcomes, complications and perioperative management in the prospective RCT

Qiqi Zhang

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