Background The efficacy of immune checkpoint inhibitors (ICIs) in advanced gastrointestinal (GI) cancers, especially microsatellite-stable tumors, is limited. Stereotactic body radiation therapy (SBRT) may enhance ICIs’ antitumor immune response by promoting immunogenic cell death. This meta-analysis evaluated the efficacy, safety, and abscopal effect of combining SBRT and ICIs in advanced GI malignancies. Methods A literature search across PubMed, Embase, and Cochrane Library up to November 23, 2025, was conducted. Primary endpoints were objective response rate (ORR) and progression-free survival (PFS); secondary outcomes included overall survival (OS), disease control rate (DCR), grade ≥3 treatment-related adverse events (TRAEs), and abscopal effect rate. Random-effects models and I² statistics were used for analysis. Results Twenty-five studies were included in the final analysis. Risk of bias assessment indicated generally high methodological quality across included studies. SBRT+ICIs significantly improved the objective response rate (OR 5.30, 95% CI: 2.19–12.84) compared to controls. The combination therapy robustly reduced the risk of death (HR 0.43, 95% CI: 0.33–0.55) and disease progression (HR 0.43, 95% CI: 0.35–0.54). Importantly, the risk of grade ≥3 treatment-related adverse events was not significantly increased compared to control groups (pooled RD -0.09, 95% CI: -0.35 to 0.18). The reported abscopal effect rate varied across studies, with a mean of 26.2%. Conclusion SBRT+ICIs improves efficacy and survival in advanced GI cancers, with manageable safety, especially in hepatocellular carcinoma. Further validation in randomized trials and optimization for less responsive tumors is needed.
Ma et al. (Tue,) studied this question.