Preventive effect of dexamethasone premedication on the development of infusion‐related reaction in breast cancer patients receiving trastuzumab

Aim To clarify the incidence and risk factors of infusion‐related reactions (IRRs) caused by trastuzumab in breast cancer patients and verify the preventive effects of dexamethasone. Methods All breast cancer patients newly treated with trastuzumab at the Osaka Medical and Pharmaceutical University Hospital from 1 January 2017 to 31 December 2020 were included. The electronic medical records were retrospectively reviewed. The outcome measure was the occurrence of IRRs of grade 1 or higher during trastuzumab infusion. Only dexamethasone and anticancer drugs administered concomitantly before trastuzumab were used as explanatory variables. Results The 176 patients included in the study received 2320 infusions. Fifty‐eight patients (33.0%) experienced IRRs, and IRRs occurred in 80 (3.4%) of the total 2320 infusions. Owing to the hierarchical structure of the data, the independence of the observed values was evaluated using the intraclass correlation coefficient. Multivariate multilevel logistic regression analysis showed that premedication with dexamethasone lowered the risk of trastuzumab‐induced IRRs (mg, per 1 unit, odds ratio [OR] = 0.61, 95% confidence interval [95% CI] 0.43‐0.85, P = .003). In addition, preoperative status (OR = 38.9, 95% CI 5.4‐278.7, P < .001) and high‐dose trastuzumab (mg/kg, per 1 unit, OR = 60.6, 95% CI 20.1‐182.9, P < .001) were independent risk factors for IRRs. Conclusion The results of this study suggest that premedication with dexamethasone exhibits preventive effects on trastuzumab‐induced IRRs in breast cancer patients. Future studies are needed to determine the optimal dose of dexamethasone to prevent IRRs and the impact of dexamethasone on the efficacy of trastuzumab in breast cancer.