Seasonal variation and risk of paclitaxel-induced hypersensitivity reactions: A retrospective cohort study.

IntroductionMany anticancer agents are associated with immediate hypersensitivity reactions, and taxanes are among the most frequently implicated drug class. Although the mechanisms underlying paclitaxel-induced hypersensitivity reactions remain incompletely understood, environmental exposures may influence immune responsiveness. Seasonal variation and associated pollen exposure may modify the risk of paclitaxel-induced hypersensitivity reactions.MethodsThis was a retrospective, single-center, Institutional Review Board-approved review of adult patients who received at least one paclitaxel infusion at our institution between November 20, 2023, and December 31, 2024.ResultsOf 2526 patients included, 554 (22%) experienced a hypersensitivity reaction to paclitaxel. The largest proportion of hypersensitivity reactions occurred during the winter months, with 29% of all hypersensitivity reactions occurring during December, January, and February. In multivariate analysis, however, fall months (September, October, November) were independently associated with increased odds of hypersensitivity to paclitaxel (OR: 1.52; 95% CI: 1.14, 2.02; p=0.029).ConclusionsSeasonal variation was associated with paclitaxel-induced hypersensitivity reactions, with fall months demonstrating increased risk in adjusted analyses. These findings are exploratory and warrant validation in larger, multicenter datasets.