Cancer Risk of Angiotensin II Receptor Blocker Valsartan: A Population-based Study

Abstract: Nitrosamine contamination of generic valsartan was found in 2018. This study aimed to investigate whether long-term use of valsartan increases cancer risk. Patients prescribed valsartan or amlodipine (control group) from 1 January 1, 2003, to June 30, 2010, were identified using the Clinical Data Analysis and Reporting System of the Hong Kong Hospital Authority, a territory-wide database in Hong Kong. Patients previously diagnosed with cancer, prescribed both medications, taking the medication, or followed up for <1 year were excluded. Cancer incidence, adjusted for age, sex, and Charlson Comorbidity Index, was the primary outcome and was estimated using Poisson regression in R version 3.6.1. Among 5023 valsartan users and 3692 amlodipine users, 887 and 740 were diagnosed with cancers during median follow-up periods of 10.97 and 12.12 years, respectively. The adjusted incidence of cancer in valsartan and amlodipine users was 165.29 (95% confidence interval 154.76–175.53) and 180.12 (167.35–193.67) per 10,000 person-years, respectively. The cancer incidence rate ratio of valsartan relative to amlodipine was 0.94 (0.88–1.01). Adjusted incidence rate ratios of valsartan relative to amlodipine were significant for breast cancer (0.63, 0.46–0.86) only. Our findings do not suggest an increase in incidence of cancer with long-term valsartan use. The duration of follow-up of more than 10 years of the study provides the reassurance that an increase in cancer risk is unlikely. Further studies are needed to elucidate the long-term effect of valsartan use on the risk of specific types of cancer.