Patient Characteristics
Before PSM, significant differences were observed among the three groups in terms of pN and pTNM stage (eTable 1, P>0.05). After PSM, no significant differences among the No.1 (n=497), No.2 (n=426), and Other groups (n=312) were observed in terms of clinicopathological characteristics, such as age, sex, BMI, ASA score, ECOG score, Charlson score, range of gastrectomy, tumor size, tumor location, cT stage, cN, cTNM, pT, pN, and pTNM stages (all P > 0.05, all Std < 0.25) (Table 1).
Perioperative Outcomes
Before PSM, the Other group had a longer operative duration compared to the No.1 and No.2 groups (No.1 vs Other = 167.9±44.8 vs 179.6±52.4; No.2 vs Other = 168.9±43.6 vs 179.6±52.4, P<0.05) (Table 2 and eTable 2). Intraoperative bleeding was significantly higher in the No.2 and Other groups compared with the No.1 group (No.1 vs No.2 = 42.1±32.3 vs 49.0±57.4; No.1 vs Other = 42.1±32.3 vs 48.6±52.1, P<0.05). There were no significant differences among the three groups in terms of lymph node harvest, time to ambulation, flatus passage, liquid diet, soft diet, or hospital stay (all P>0.05). No significant differences were found among the three groups in terms of overall, surgery-related, or non-surgery-related complications (all P>0.05). After matching, the Other group had a longer operative duration compared to the No.1 and No.2 groups (No.1 vs Other = 168.1±45.0 vs 178.5±50.9; No.2 vs Other = 172.3±53.5 vs 178.5±50.9, P<0.05). Intraoperative bleeding was significantly higher in the No.2 and Other groups compared with the No.1 group (No.1 vs No.2 = 42.8±32.3 vs 47.6±48.1; No.1 vs Other = 42.8±32.3 vs 48.5±52.4, P<0.05) (Table 2 and eTable 2). Postoperative complications were observed in 69 (22.6%), 65 (21.6%), and 67 (21.8%) patients in the No.1, No.2 and Other groups, respectively, with no significant difference in the overall complication rate among the three groups (P>0.05). Further stratified analysis showed that 38 (12.3%), 42 (13.6%), and 38 (12.3%) patients in the No.1, No.2, and Other groups, respectively, had surgery-related complications, and 31 (10.2%), 29 (9.6%), and 31 (10.2%) had non-surgery-related complications, with no statistically significant differences (eTable 3, all P>0.05).
Long-term Prognosis
The median follow-up period was 52 months (range,1–90 months). The Kaplan-Meier survival curve revealed comparable five-year OS (83.7%, 80.3%, and 82.8%, P=0.312) and DFS (78.6%, 76.2%, and 77.2%, P=0.437) in the No.1, No.2, and Other groups, respectively (Fig. 2). Univariate Cox regression analysis revealed that age, range of surgery, tumor size, tumor location, pT stage, and pN stage were significant risk factors for OS (all P<0.05), and age, range of surgery, pT stage, and pN stage were significant risk factors affecting DFS in patients with GC (all P<0.05). Further multivariate Cox analysis suggested that age >65 years, total gastrectomy, and pT2-4 stage were independent risk factors for poor OS and DFS (P<0.05), whereas surgical case order was not an independent factor affecting the 5-year OS and DFS in patients with GC (P>0.05) (Table 3 and 4).
Survival After Surgery in High-Risk Patients
Further subgroup analyses were based on independent risk factors affecting patient OS in terms of age, gastrectomy range, and pT stage. The Kaplan-Meier survival curve showed no significant difference in 5-year OS and DFS among the three groups in those aged >65 years (eFig1); no significant difference in 5-year OS and DFS among the three groups in patients with pT stage 2–4 (eFig2); and no significant difference in 5-year OS and DFS among the three groups in patients who underwent total gastrectomy (eFig3, all P>0.05).