The impact of immune checkpoint inhibitors on infection in patients with solid malignancies: a systematic review and meta-analysis of randomised controlled trials.

Background: Immune checkpoint inhibitors (ICIs) revolutionised cancer treatment but may alter infection risk. The effect of ICIs on infection susceptibility remains unclear. Methods: We searched PubMed, the Cochrane Library, and EMBASE from database inception to October 10, 2025 for randomised controlled trials (RCTs). The primary endpoint was the risk ratio (RR) of all-grade infections; the secondary endpoint was the RR of severe (Grade 3-5) infections. Stratified analyses by ICI agent, regimen, treatment timing, infection site, and cancer type were performed separately for treatment-emergent adverse events (TEAEs) and treatment-related adverse events (TRAEs). Publication bias was assessed using funnel plots, Egger's test, and trim-and-fill; heterogeneity was evaluated by Findings: A total of 141 RCTs (87,484 participants) were included. In TEAE-based analyses, ICIs were associated with increased risks of any-grade infections [RR = 1.25; 95% confidence interval (CI): 1.12-1.39; Interpretation: The relationship between ICI therapy and infection risk is nuanced and context-dependent. In symmetric comparisons, ICIs are associated with modestly increased TEAE- and TRAE-based infection risks. This risk should be weighed against the expected survival benefit, underscoring the need for individualised assessment. Future prospective studies with time-to-event analyses and standardised infection surveillance are needed to clarify the temporal relationship between ICI exposure and infection risk. Funding: There was no funding source for this study.