U.S. Cancer-Specific Mortality Trends After Early Immune Checkpoint Inhibitor Approvals: An Ecological...

IntroductionImmune checkpoint inhibitors (ICIs) were introduced at different times across cancer types, but whether early approvals coincided with cancer-specific changes in national mortality remains uncertain.MethodsWe conducted an ecological observational comparative time-series study using CDC WONDER United States Cancer Statistics mortality data from 1999-2019. We analyzed CDC-calculated age-adjusted mortality rates (AAMRs) for melanoma of the skin, lung and bronchus, kidney and renal pelvis, urinary bladder, and Hodgkin lymphoma. Cancer-specific synthetic-control models used each site's first major ICI approval year, preperiod-centered log AAMR trajectories, mutually exclusive solid or hematologic comparison sites, and a common 0-3-year postapproval estimand. Placebo analyses and staggered-adoption difference-in-differences (DiD) were robustness checks.ResultsObserved AAMRs averaged 3.44%, 13.05%, 4.73%, 3.60%, and 3.68% below synthetic estimates for melanoma, lung, kidney, bladder, and Hodgkin lymphoma, respectively. Conditional placebo-rank pseudo-P values were .40, .23, .25, .20, and 1.00. Temporal-placebo models showed earlier divergence for several sites. The balanced 0-3-year DiD estimate was -0.96 deaths per 100,000 (95% pointwise CI, -2.99 to 1.06).ConclusionCancer-specific mortality patterns were directionally compatible with lower mortality during early ICI approval eras, but placebo benchmarking, heterogeneous temporal specificity, and an imprecise DiD estimate precluded firm causal attribution. These ecological findings do not estimate individual treatment effectiveness or current ICI practice.