Summary

There has been growing interest in studying the biologicaleffects of certain drugs and their potential to reduce the risk ofvarious cancers. One study reported a decrease in the incidenceof urogenital cancers in a trial with patients whoreceived warfarin for treatment of venous thromboembolism,but a limitation to this study of urogenital cancers was the verysmall number of bladder cancer cases that developed followingwarfarin therapy. The objective of the present study is to measurethe association between warfarin use and bladder cancer. Atotal of 330 cases with bladder cancer were identified at theJames A. Haley Veterans’ Administration (VA) Hospital in Tampa,Florida, using a combination of computerized pathology records and inpatient and outpatient diagnoses. Controls wererandomly selected from the VA computerized administrativedatabase and 1293 controls were included for analysis.Unconditional logistic regression analysis was performed toassess the risk of bladder cancer after adjusting for age, gender,and cigarette smoking. Among warfarin users, although therewas a 27% elevation in risk, it did not differ significantly fromnonusers (OR = 1.27, 95% CI = 0.85, 1.89). No duration-responserelationship was observed between anticoagulant useand risk of bladder cancer. The results suggest that warfarindoes not protect against bladder cancer, at least in male smokers,the highest risk population for bladder cancer.