Pathological and oncological outcomes of pylorus-preserving versus conventional distal gastrectomy in early gastric cancer: a systematic review and meta-analysis

BACKGROUND: Pylorus-preserving gastrectomy (PPG) is a function-preserving surgery for the treatment of early gastric cancer (EGC) in the middle third of the stomach. According to the literature reports, PPG decreases the incidence of dumping syndrome, bile reflux, gallstone formation, and nutritional deficit compared with conventional distal gastrectomy (CDG). However, the debates about PPG have 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 ratios (ORs) for dichotomous variables and weighted mean differences (WMDs) for continuous variables. For all outcomes, 95% confidence intervals (CIs) were calculated. 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 the CDG group, the PPG group had fewer lymph nodes harvested (WMD= −3.09; 95% CI −4.75 to −1.43; P < 0.001). Differences in the number of resected lymph nodes were observed at stations No. 5, No. 6, No. 9, and No. 11p. There were no differences in lymph node metastasis at 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 the 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 = 0.63; 95% CI 0.24 to 1.67; P = 0.852) or recurrence-free survival (HR = 0.29; 95% CI 0.03 to 2.67; P = 0.900). CONCLUSIONS: The meta-analysis of existing evidence demonstrated that the survival outcomes of PPG may be comparable to those of CDG. However, fewer lymph nodes at stations in No. 5, No. 6, No. 9, and No. 11p were harvested with PPG. We also found shorter proximal resection margins and distal resection margins for PPG, meaning more remnant stomachs would be preserved in PPG. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12957-022-02766-0.