Table 1_Microsatellite instability combined with PD-L1 expression in prognosis of gastric cancer: an integrated analysis based on individual patient data.docx

For OS, MSI-H alone (HR = 0.500, 95%CI: 0.357-0.700, P < 0.001), and MSI-H/MSI-L combined (HR = 0.641, 95%CI: 0.437-0.939, P = 0.025) were associated with better outcomes than MSS; PD-L1 positivity predicted poorer OS (HR = 1.517, 95%CI: 1.077-2.137, P = 0.017); MSI-H+PD-L1 negative patients had the most favorable OS (HR = 0.380, 95%CI: 0.255-0.566, P < 0.001), while MSI-H+PD-L1 positive patients had poorer OS than MSS+PD-L1 negative patients (HR = 2.076, 95%CI: 1.238-3.479, P = 0.006).

For DFS, MSI-H alone (HR = 0.506, 95%CI: 0.360-0.710, P < 0.001) and MSI-H/MSI-L combined (HR = 0.530, 95%CI: 0.402-0.698, P < 0.001) outperformed MSS, but PD-L1 expression showed no significant DFS association (HR = 1.189, 95%CI: 0.472-2.998, P = 0.709). Subgroup analyses identified TNM stage, Lauren classification, chemotherapy timing, and MSI detection method as significant effect modifiers (all interaction P < 0.05).

Pooled immunotherapy data showed that MSI-H patients had higher ORR than MSS (OR = 3.580, P < 0.001), and MSI-H+PD-L1 positive patients achieved the highest response rates (OR = 4.100 vs. MSI-H+PD-L1 negative, P < 0.001). Sensitivity analysis confirmed result stability, and publication bias was minimal.</p>Conclusion<p>MSI-H status is a robust favorable prognostic factor for GC, while PD-L1 positivity indicates adverse OS prognosis.

The combination of MSI and PD-L1 expression enables refined prognostic stratification of GC patients.</p>