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Do Calcium Channel Blockers Cause Cancer?

Calcium channel blockers can interfere with apoptosis, or regulated cell death, one of the body's defenses against cancer. In this prospective cohort study, investigators followed 5052 patients over age 70 for an average of 3.7 years and examined the incidence of cancer in 451 patients who took calcium blockers versus 4601 who did not.

At baseline, patients on calcium channel blockers had higher rates of cardiovascular disease and disability, and lower diastolic blood pressure. Calcium channel blocker users were 1.72 times more likely to develop cancer, after adjustment for confounders. This effect was significant for verapamil and nifedipine, but not for diltiazem. Dose-response analysis confirmed that patients taking higher doses had higher risk. Calcium blockers were significantly associated with cancers of the uterus and adnexa, lymphatic system, and hematopoietic system; risk was also increased for cancers of the stomach, prostate, colon, breast, and urinary tract. Careful multivariate analysis failed to identify any other pharmacologic correlates with cancer.

Comment: This study and others fuel the calcium channel blocker controversy. Like prior epidemiologic studies associating these agents with increased cardiac mortality among hypertensives, this study has limitations. Patients on calcium blockers had more frequent admissions, leading to a greater opportunity for cancer detection. Also, shorter-acting regimens were used in this study than are currently prescribed. Finally, patients on calcium blockers may have had a condition predisposing them to cancer. Only careful prospective, randomized trials can provide the answers.

— KA Eagle

Published in Journal Watch Cardiology November 1, 1996

Citation(s):

Pahor M et al. Calcium-channel blockade and incidence of cancer in aged population. Lancet 1996 Aug 24 348 493-497.

• Medline abstract (Free)