Prospective Multicenter Randomized Controlled Trial Comparing Reduced-Port Robotic and Conventional Laparoscopic Subtotal Gastrectomy for Early Gastric Cancer (REPROG-RCT)

"Study objective The objective of this study is to evaluate whether reduced-port robotic subtotal gastrectomy demonstrates non-inferiority in safety, specifically regarding the incidence of postoperative complications, compared to conventional laparoscopic subtotal gastrectomy in patients with early gastric cancer. Additionally, the study aims to assess differences in efficacy between the two surgical approaches as secondary endpoints.

Study design overview This study is a multicenter, randomized controlled trial involving patients with early gastric cancer. Participants will be randomly assigned in a 1:1 ratio to either the reduced-port robotic surgery group or the conventional laparoscopic surgery group. Outcomes to be observed over a 30-day postoperative period include the incidence of complications, operative time, blood loss, pain levels, length of hospital stay, and quality of life.

Investigational Product/Medical Device Robotic surgical platform Laparoscopic surgical platform Target Sample Size and Rationale The study aims to demonstrate that reduced-port robotic subtotal gastrectomy (experimental group) is non-inferior to conventional laparoscopic subtotal gastrectomy (control group) with respect to the incidence of postoperative complications of grade ≥ 3.

Previous studies have reported that the complication rate for minimally invasive subtotal gastrectomy in early gastric cancer is approximately 4%.

For the non-inferiority test based on comparison of proportions, the following assumptions were used to calculate the required sample size:

• Complication rate in the control group (pC): 4%
• Complication rate in the experimental group (pT): 4%
• Non-inferiority margin (Δ): 5%
• Significance level (α): 2.5% (one-sided)
• Statistical power (1-β): 80%
• Allocation ratio: 1:1
• Expected dropout rate: 10%

Based on these assumptions, the calculated sample size is 242 patients per group. Considering a 10% dropout rate, the adjusted sample size is 269 patients per group, totaling 538 patients for the entire study.Inclusion:

Patients aged 20 to 80 years diagnosed with early gastric cancer (cT1N0) who are eligible for distal subtotal gastrectomy based on endoscopic or imaging findings.

Exclusion:

Presence of distant metastasis Diagnosis of advanced gastric cancer Suspected lymph node metastasis History of previous gastrectomy ASA physical status score > 3 Pregnancy or withdrawal of informed consent Randomization will be performed preoperatively using a web-based system. Surgical procedures will be conducted in accordance with standardized operative guidelines.

Follow-up assessments will be conducted at discharge, on postoperative day 30, and at 3 and 6 months postoperatively.

Endpoints

Primary Endpoint:

Incidence of postoperative complications of Clavien-Dindo grade ≥ III within 30 days after surgery

Secondary Endpoints:

Operative time Estimated blood loss Number of harvested lymph nodes Length of hospital stay Postoperative pain scores Quality of life (including wound-related discomfort and dietary function) Three-year disease-free survival rate Data analysis and statistical Methods Analyses will be conducted on an intention-to-treat (ITT) basis. Categorical variables will be analyzed using the χ² test or Fisher's exact test, as appropriate.

Continuous variables will be analyzed using either the t-test or the Mann-Whitney U test, depending on the distribution of the data.

Survival analyses will be performed using Kaplan-Meier curves and compared with the log-rank test.

Non-inferiority testing will be based on comparisons of 95% confidence intervals.