Drug Saf. 2026 Jan 19. doi: 10.1007/s40264-025-01645-3. Online ahead of print.
ABSTRACT
BACKGROUND: Previous evidence suggests a potential protective effect of warfarin against cancer, compared to non-users. However, it may be prone to immortal time bias and residual confounding.
OBJECTIVE: We aimed to examine the association between cancer and warfarin, compared with active comparator (direct oral anticoagulants).
METHODS: We conducted studies using population-based databases from England and Hong Kong to investigate the association between warfarin and hazard of cancer using a new-user active-comparator cohort design. People with atrial fibrillation aged ≥ 18 years who had first received anticoagulant treatment during 01/01/2011-31/12/2019 were involved.
RESULTS: No evidence supported the association between warfarin and hazard of overall cancer, compared with direct oral anticoagulants in both settings (England: hazard ratio [HR] = 1.03, 95% confidence interval [CI] 0.94-1.13; Hong Kong: HR = 0.89, 95% CI 0.79-1.01). A lower hazard of female breast (HR = 0.49, 95% CI 0.30-0.79), ovarian (HR = 0.07, 95% CI 0.01-0.58), and pancreatic (HR = 0.46, 95% CI 0.22-0.96) cancers and a higher hazard of kidney cancer (HR = 3.57, 95% CI 1.64-7.76) were found in Hong Kong, comparing warfarin with direct oral anticoagulants, but these were not replicated in England.
CONCLUSIONS: This study does not find a protective effect of warfarin against cancer versus direct oral anticoagulants. The risks of site-specific cancers including pancreatic, kidney, and sex-specific cancers between oral anticoagulants shown in the Hong Kong setting only may require further investigation in other independent datasets.
PMID:41553598 | DOI:10.1007/s40264-025-01645-3
