The role of H1 antihistamines in contralateral breast cancer: a Danish nationwide cohort study
Menée au Danemark à partir de données portant sur 52 723 patientes atteintes d'un cancer du sein diagnostiqué entre 1996 et 2012 (âge : au moins 20 ans ; durée de suivi : 310 583 personnes-années), cette étude analyse l'association entre une utilisation après diagnostic d'antihistaminiques H1 et le risque de cancer du sein controlatéral (1 444 cas)
Background: Preclinical studies have shown both pro- and antineoplastic effects of antihistamines. Here, we evaluated the effect of H1 antihistamines on contralateral breast cancer (CBC) risk, and whether cationic amphiphilic (CAD) antihistamines could increase the sensitivity to chemotherapy. Methods: From the Danish Breast Cancer Group clinical database, we identified all women aged ≥20 years with a first-time diagnosis of breast cancer during 1996–2012. Information on drug use, CBC and potential confounding factors was retrieved from nationwide registries. Using Cox proportional hazard regression models, we calculated hazard ratios (HRs) and 95% confidence intervals (CIs) for CBC associated with H1-antihistamine use. Results: We identified 52,723 patients with breast cancer with a total of 310,583 person-years of follow-up. Among them, 1444 patients developed a new primary tumour in the contralateral breast. Post-diagnosis use of H1 antihistamines (≥2 prescriptions) was not strongly associated with CBC risk (HR 1.08, 95% CI: 0.90–1.31) compared with non-use (<2 prescriptions). Use of CAD antihistamines among patients receiving chemotherapy was not associated with a decrease in CBC risk. Conclusions: Taken together, our findings do not suggest any association of H1-antihistamine use with CBC development.