Abstract
BACKGROUND: Early studies indicated that corticosteroids may limit the survival benefit from immunotherapy. We conducted this systematic review to evaluate the effect corticosteroids have on immunotherapy in patients with malignancy, when adjusted for potentially confounding effects of corticosteroids given for palliative indications. METHODS: Three electronic databases (PubMed, Embase and Medline) were searched on 1 February 2023. Studies that measured response or survival to immunotherapy in people receiving corticosteroids for non-cancer indications compared to either no corticosteroids or corticosteroids for cancer-related indications were included. Studies exclusively evaluating the effect of corticosteroids administered for immune-related adverse events (irAE) were excluded to avoid immortal time bias. Pooled odds and hazard ratios with 95% confidence intervals (CI) were calculated using a random effects model. Study heterogeneity was assessed using the I(2) statistic, and publication bias was evaluated by funnel plot and Egger's regression model. RESULTS: Eight thousand four hundred and twenty-six titles were identified on our search. Eight studies met our inclusion criteria for meta-analysis. Administration of corticosteroids does not have a statistically significant effect on survival and response to immunotherapy when administered for non-cancer-related indications, with a pooled odds ratio for overall response rate 1.01 (95% CI 0.64-1.60); pooled hazard ratio (HR) for progression free survival 0.87 (95% CI 0.68-1.12); and pooled HR for overall survival 0.79 (95% CI 0.59-1.05). CONCLUSION: This systematic review indicates that administration of corticosteroids does not affect response to immunotherapy nor survival outcomes, when removing confounding palliative corticosteroid indications. These results are limited by the retrospective nature of the studies included, small sample sizes, lack of information about corticosteroid dosing and the inclusion of irAE in two of the studies which could bias the results.