Does Malignant Ascites Define Prognosis in Gastric Cancer with Peritoneal Spread? A Systematic Review and Meta-analysis.

Background: Gastric cancer (GC) is the fifth most common cancer and a leading cause of cancer-related death. Peritoneal metastases occur in up to 25% of patients, with nearly half developing malignant ascites (MA), which arises from lymphatic obstruction, vascular permeability, and immune dysregulation. Median overall survival (OS) in this setting is poor (2-8 months). This systematic review and meta-analysis evaluate the prognostic impact of ascites in metastatic GC.

Materials and methods: PubMed, Embase, and Cochrane were searched for studies reporting OS in metastatic GC patients with and without ascites. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated using fixed and random-effects models in RStudio 4.2.3.

Results: Overall, 14 studies involving 2179 patients, with 1208 having ascites, were included in the analysis. Of these, 13 were retrospective studies and 1 was a prospective study. The presence of ascites was associated with a significantly worse prognosis compared to its absence (HR 1.8418; 95% CI 1.5657-2.1667; P < 0.001). Similarly, the comparison of massive type ascites with mild to moderate type shows a worse outcome for the higher grade of ascites (HR 1.8597; 95% CI 1.4633-2.3635; P < 0.001). Comparing no to moderate ascites vs massive ascites, the massive type also shows a significantly lower overall survival (HR 2.5114; 95% CI 1.5409-4.0931; P < 0.001).

Conclusions: This meta-analysis suggests that the presence of ascites and its grades are essential prognostic factors for metastatic gastric cancer, significantly worsening overall survival.