Liver cancer risk in the context of today's hormonal contraceptives

Combined oestrogen-progestin oral contraceptives are classified as hepatic carcinogens based largely on older studies of outdated formulations, creating uncertainty about risks of contemporary hormonal contraceptives. We conducted a Danish nationwide registry-based cohort study including 1,957,490 women aged 15 to 49 years followed from 1995 to 2021 to examine current hormonal contraceptive use and liver cancer risk. Use was assessed as a time-dependent exposure using prescription data, and cancer diagnoses were identified through Danish Cancer Registry. Adjusted incidence rate ratios (IRRs) were estimated using Poisson regression. During 24.5 million person-years of follow-up, 130 women developed liver cancer. Ever use of hormonal contraception was not associated with liver cancer risk (IRR = 0.76, 95% CI = 0.50 to 1.15), nor were current use, product type, duration, or time since last use. Findings suggest that contemporary hormonal contraceptives are not associated with increased liver cancer risk and support reassessment of existing carcinogenic classifications.