Systematic review registration number
Our systematic review protocol has been registered in the International Prospective Register of Systematic Reviews (PROSPERO, www.crd.york.ac.uk/prospero/, registration number: CRD42020179779)
En bloc resection was defined as a one-piece resection of the entire lesion as observed endoscopically(14). R0 resection was defined the lesion was removed as one piece with pathologically negative margins(15). Curative resection was achieved when both the lateral and vertical margins of the specimen were free of cancer and there was no invasion deeper than 1000 µm from the muscularis mucosae, lymphatic invasion, vascular involvement, or poorly differentiated component(16). The dissection speed (mm2/min) was defined as the specimen area (mm2) divided by duration (min). Recurrence was defined as the lesion detected in the follow-up after surgery. Complications include muscular injury, perforation, intraoperative and postoperative bleeding.
Jianglei Li and Yuyong Tan performed the literature search and data extraction. PubMed, Cochrane Library, Web of Science, Embase, Wanfang and CNKI databases were searched, including all entries from the inception of the database up to and including 9 February 2021. The following search terms were used: ‘endoscopic submucosal tunnel dissection’, ‘ESTD’, ‘endoscopic submucosal dissection’, ‘ESD’, ‘stomach’ and ‘gastric’. We searched free terms as well as MeSH words, and we reviewed the references of all retrieved studies to identify any other relevant literature.
Electronic search strategy for PubMed: ((endoscopic submucosal tunnel dissection) OR ESTD) AND ((endoscopic submucosal dissection) OR ESD) AND ((stomach) OR (gastric))
Studies meeting the following criteria were included: (a) studies involving patients diagnosed with gastric lesions and treated with ESTD or ESD, (b) studies conducted to compare ESTD and ESD in gastric lesions, and (c) studies reporting clinical outcomes after ESTD or ESD, including en bloc resection rate, R0 resection rate, curative resection, specimen area, operation time, dissection speed, complications and recurrence. The exclusion criteria were: (a) case reports, reviews, or conference abstracts, (b) studies lack of sufficient data.
Data extraction and quality evaluation
The titles and abstracts of articles were screened independently by two reviewers and the following information was extracted: author names, study design, publication year, study period, region, number of patients, baseline characteristics of patients, clinical outcome data including en bloc resection rate, R0 resection rate, curative resection rate,complications, operation time, dissection speed and recurrence rate. Study quality was assessed using the Newcastle–Ottawa Quality Assessment Scale (NOS); studies with NOS scores of more than six points were considered high-quality articles.
A fixed-effects model was used for data analysis, except when data were considered significantly heterogeneous. In that case, a random-effects model was used. We chose odds ratios (ORs) to evaluate differences in en bloc resection rate, R0 resection rate and curative resection rate between the ESTD and ESD groups. And we chose weighted mean differences (WMDs) for specimen area, operation time and dissection speed. P values less than 0.05 were considered significant. Statistical heterogeneity was assessed using Q2 tests and Higgins I2 statistics. Values of P < 0.10 or I2 > 50% indicated statistical significance. In case of statistically insignificant heterogeneity, a fixed-effects model was adopted. Otherwise, a random-effects model was applied. All statistical analyses were performed using Stata 14 (Stata Corp., College Station, Texas, USA). Begg’s test was performed to assess publication bias on the en bloc resection rate.