A systemic analysis was performed to evaluate the prognostic utility of the Glasgow prognostic score (GPS) and the modified (m)GPS in cancer patients treated with immune checkpoint inhibitors (ICI). The PubMed, Cochrane Library, EMBASE and Google Scholar databases were searched for entries added until May 1st, 2023, to obtain relevant articles for this study. The analysis examined several clinical outcomes, including overall survival (OS), progression-free survival (PFS), objective response rate and disease control rate (DCR). In this analysis, a total of 38 articles with 3,772 patients were included. The pooled results indicated that patients with high GPS levels had shorter OS [GPS 2 vs. 0, hazard ratio (HR): 4.35, P<0.001; GPS 1 vs. 0, HR: 2.00, P<0.001; GPS 2 vs. 1/0, HR: 2.62, P<0.001; GPS 2/1 vs. 0, HR: 2.60, P<0.001) and PFS (GPS 2 vs. 0, HR: 2.11, P=0.001; GPS 1 vs. 0, HR: 1.33, P=0.001; GPS 2 vs. 1/0, HR: 2.11, P<0.001; GPS 2/1 vs. 0, HR: 1.62, P<0.001], as well as a lower DCR [GPS 2 vs. 1/0, odds ratio (OR): 0.53, P<0.001, GPS 2/1 vs. 0, OR: 0.51, P<0.001]. It was also found that patients with high mGPS levels had poorer OS (mGPS 2 vs. 0, HR: 3.15, P<0.001; mGPS 1 vs. 0, HR: 1.70, P<0.001; mGPS 2 vs. 1/0, HR: 1.95, P=0.049; mGPS 2/1 vs. 0, HR: 3.14, P=0.041; continuous variables, HR: 1.52, P<0.001) and PFS (mGPS 2 vs. 0, HR: 2.70, P<0.001; mGPS 1 vs. 0, HR: 1.74, P=0.016; mGPS 2 vs. 1/0, HR: 1.91, P=0.044; continuous variables, HR: 1.29, P<0.001), and lower DCR (mGPS 2 vs. 1/0, HR: 0.46, P<0.001). In conclusion, the GPS and mGPS were reliable predictors of outcomes in cancer patients treated with ICIs.Copyright: © 2025 Ye and Li.