Does amlodipine increase cancer incidence?

To the Editor: The Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial (PREVENT)1 amplifies the controversy over calcium antagonists and increased cancer risk.2 In this 36-month, placebo-controlled, randomized trial, the calcium antagonist amlodipine had no effect on the angiographic progression of coronary atherosclerosis or on the risk of major cardiovascular events. In the group assigned to amlodipine, the annualized rates of coronary artery bypass grafting and unstable angina were reduced by 1.0% and 2.1%, respectively. Unfortunately, incident cancers increased in the group assigned to amlodipine. The annualized rate of incident cancers was 1.8% in the amlodipine group and 1.0% in the placebo group. Thus, the 0.8% annualized increase in incident cancer in the amlodipine group was similar in magnitude but opposite in direction to the 1.0% annualized reduction in coronary artery bypass surgery. Because some observational data suggest that calcium antagonists may cause cancer,2 this finding in PREVENT warrants further investigation. From a public health perspective, for every 1 million patients taking amlodipine for 1 year, the incident cancer rate will increase by 8000 because of the drug. Perhaps we are trading one problem for another.