Long-Term Calcium-Channel Blocker Use for Hypertension Associated With Higher Breast Cancer Risk
Long-term use of a calcium-channel blocker to treat hypertension is associated with higher breast cancer risk, according to a report published by JAMA Internal Medicine. The study assessed the relationships between the major classes of hypertensive agents and risk of the two most common histologic types of breast cancer in postmenopausal women with long histories of hypertensive use.
Antihypertensive medications are the most commonly prescribed class of drugs in the United States and in 2010 totaled an estimated 678 million filled prescriptions, Christopher I. Li, MD, PhD, of the Fred Hutchinson Cancer Research Center, Seattle, and colleagues wrote in the study background. However, despite the widespread use of these agents, there have been few studies examining the relationship between different types of antihypertensives and breast cancer risk, and results are inconsistent.
Study Details
The population-based study in the three-county Seattle–Puget Sound metropolitan area included women aged 55 to 74 years; 880 of the women had invasive ductal breast cancer, 1,027 had invasive lobular breast cancer, and 856 had no cancer and served as the control group. Researchers measured the risk of breast cancer and examined the recency and duration of use of antihypertensive medications.
According to the results, current use of calcium-channel blockers for 10 or more years was associated with higher risks of ductal breast cancer (odds ratio [OR] = 2.4, 95% confidence interval [CI] = 1.2–4.9; P = .04 for trend) and lobular breast cancer (OR = 2.6, 95% CI = 1.3–5.3; P = .01 for trend). The relationship did not vary much based on the type of calcium-channel blockers used (short-acting vs long-acting or dihydropyridines vs nondihydropyridines). Other antihypertensive medications—diuretics, beta-blockers, and angiotensin II antagonists—were not associated with increased breast cancer risk, the results indicated.
“While some studies have suggested a positive association between calcium-channel blocker use and breast cancer risk, this is the first study to observe that long-term current use of calcium-channel blockers in particular [is] associated with breast cancer risk. Additional research is needed to confirm this finding and to evaluate potential underlying biological mechanisms,” the study concluded.
Convincing Data
In a related commentary, Patricia F. Coogan, ScD, of the Slone Epidemiology Center at Boston University, wrote that although the study by Dr. Li and colleagues is observational and cannot prove causality, “the data make a convincing case that the hypothesis that long-term [calcium-channel blocker] use increases the risk of breast cancer is worthy of being pursued.… If true, the hypothesis has significant clinical and public health implications.”
This study was funded by the National Cancer Institute and the U.S. Department of Defense.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
