Background: Pylorus-preserving gastrectomy (PPG) is a function-preserving surgery for the treatment of early gastric cancer (EGC) in the middle third. According to literature reports, PPG decreased the incidence of dumping syndrome, bile reflux, gallstone formation, and nutritional deficit in comparison with conventional distal gastrectomy (CDG). However, the debates about PPG has been dominated by the incomplete lymphadenectomy and oncological safety. We carried out a systematic review and meta-analysis to evaluate the pathological and oncological outcomes of PPG.
Methods: The protocol was registered in PROSPERO under number CRD42022304677. Databases including PubMed, Embase, Web of science and the Cochrane Register of Controlled Trials were searched before February 21,2022. The outcomes included the pooled odds ratio (OR) for dichotomous variables and weighted mean differences (WMDs) for continuous variables. All outcomes were calculated with 95% confidence intervals (CI). Meta-analysis was performed using STATA software (Stata 14, Stata Corporation, Texas) and Review Manager 5.4.
Results: A total of 4500 patients from 16 studies were included. Compared with CDG, PPG group has less lymph nodes harvested (WMD=-3.09; 95% CI -4.75 to -1.43; P<0.001). Differences of resected lymph nodes were observed in No.5, No.6, No.9 and No.11p stations. There were no differences in lymph nodes metastasis of each station. Shorter proximal resection margins (WMD= -0.554; 95%CI, -0.999 to -0.108; P=0.015) and distal resection margins (WMD= -1.569; 95% CI -3.132 to -0.007; P=0.049) were observed in PPG group. There were no significant differences in pathological T1a stage (OR=0.99; 95% CI 0.80 to 1.23; P=0.88), T1b stage (OR=1.01; 95% CI 0.81 to 1.26; P=0.88), N0 stage (OR=0.97; 95% CI 0.63 to 1.48; P=0.88), tumor size (WMD = -0.10; 95% CI, -0.25 to 0.05; P = 0.187), differentiated carcinoma (OR=1.04; 95% CI 0.74 to 1.47; P=0.812) or signet ring cell carcinoma (OR=1.22; 95% CI 0.90 to 1.64; P=0.198). No significant differences were observed between the groups in terms of overall survival (HR=0.22 95%CI 0.01 to 6.69; P=1.000) and recurrence free survival (HR=0.31; 95%CI 0.00 to 24.35; P=0.687).
Conclusions: The meta-analysis of existing evidence demonstrated that PPG had comparable survival outcomes with CDG. However, PPG harvested less lymph nodes in No.5, No.6, No.9 and No.11p stations. We also found that PPG has shorter proximal resection margin and distal resection margin, meaning more remnant stomach would be preserved in PPG.