CALCIUM-CHANNEL BLOCKERS AND RISK OF CANCER

Background Previous studies have been interpreted as suggesting an inc rease in risk of cancer among users of calcium-channel blockers compar ed with users of beta-blockers. To explore this issue further, we stud ied a large group of hypertensive patients to investigate the relation of calcium-channel blockers and cancer. Methods In cohorts of users o f calcium-channel blockers, angiotensin-converting-enzyme (ACE) inhibi tors, and beta-blockers, we identified all cases of cancer diagnosed i n 1995, We used a nested case-control analysis to estimate the risk of cancer among users of calcium-channel blockers and ACE inhibitors, wi th users of beta-blockers as a reference group. The study was based on information taken from the General Practice Research Database, and th e study population was restricted to patients with at least 4 years of medical history recorded on computer. Findings The study was based on 446 cases of cancer and 1750 controls. The relative risk estimates fo r all cancers combined were 1.27 (95% CI 0.98-1.63) and 0.79 (058-106) for users of calcium-channel blockers and ACE inhibitors, respectivel y, relative to users of beta-blockers. There was little difference in risk estimates with duration of use of calcium-channel blockers of les s than 1.0 year (relative risk 1.46), 1.0-3.9 years (1.26), and 4.0 ye ars or more (1.23). Interpretation The small positive association betw een calcium-channel blockers and risk of cancer is unlikely to be caus al since there is no increase in risk with increasing duration of calc ium-channel blocker use.