The association between pathological complete response and prognosis of gastric or adenocarcinoma of esophagogastric junction cancer following neoadjuvant chemotherapy: A meta-analysis.

[OBJECTIVE] To evaluate the prognostic value of pathological complete response (pCR) in patients with gastric cancer (GC) and adenocarcinoma of the esophagogastric junction (AEG) after neoadjuvant chemotherapy (NACT).

[METHODS] PubMed, Embase, Cochrane Library, and Web of Science were systematically searched from inception to August 2024. The primary outcome was assessed by overall survival (OS), with progression-free survival (PFS) and disease-free survival (DFS) as secondary outcomes. Hazard ratios (HR) and 95 % confidence intervals (CI) were calculated. We analyzed OS, PFS, and DFS across different tumor regression grade (TRG) systems and performed a subgroup analysis, categorizing studies into pCR (Mandard 1/Becker 1a/the Japanese Gastric Cancer Association (JCGC) 3/the College of American Pathologists (CAP) 0) and major pathological response (MPR) (Mandard 1-2/Becker 1a-1b/JCGC 2-3/CAP 0-1).

[RESULTS] Twenty-five studies (20,503 patients) were included. Achieving pCR significantly correlated with improved survival across all TRG systems: Mandard system (PFS: HR = 0.38, 95 % CI: 0.21-0.68, p = 0.001; DFS: HR = 0.31, 95 % CI: 0.21-0.48, p < 0.001), Becker system (OS: HR = 0.63, 95 % CI: 0.43-0.93, p = 0.005; PFS: HR = 0.42, 95 % CI: 0.21-0.85, p = 0.015; DFS: HR = 0.34, 95 % CI: 0.21-0.57, p < 0.001). Significant associations were also observed for JCGC and CAP systems. Subgroup analysis revealed a strong survival benefit from achieving pCR in the "pCR" subgroup, but no significant correlation in the "MPR" subgroup.

[CONCLUSIONS] This meta-analysis indicated that pCR is closely associated with improved survival outcomes in GC and AEG patients following NACT, particularly under the Becker system, which is the most widely used system today. However, the prediction of survival may vary among various TRG systems.