Calcium channel blockers linked to breast cancer: Should women stop taking the drugs?
Women taking drugs known as calcium channel blockers (CCBs) for high blood pressure and other health conditions may be at higher risk for breast cancer if the drug is used long-term, according to a study published in the Journal of the American Medical Association (JAMA).
The finding is particularly important because so many people take drugs to lower blood pressure. It’s also important because studies about risk of breast cancer from the drugs that are the most commonly prescribed medication in the U.S. have yielded inconsistent results.
Christopher I. Li, M.D., Ph.D., of the Fred Hutchinson Cancer Research Center, Seattle and colleagues found taking calcium channel blockers for more than 10-years was associated with higher odds of ductal breast cancer.
The analysis comes from a population based study that included women ages 55 to 74 years from the three county metropolitan Seattle-Puget Sound regions.
The researchers looked at the women’s breast cancer risk and use of the blood pressure medications, finding higher odds of the disease with 10 or more years of use.
Patricia F. Coogan, Sc.D., of the Slone Epidemiology Center at Boston University, wrote in a commentary to the sutdy that though the finding is observational and doesn't show calcium channel blockers cause breast cancer, there would be public health implications, if it’s true.
The study authors say more research is needed to confirm the finding and to understand how the medications could lead to breast cancer.
She says it doesn't mean women should stop taking their blood pressure medications, but says the finding is“… valid evidence supporting the hypothesis that long-term CCB use increases the risk of breast cancer.” Coogan suggests the study also doesn't mean clinicians should change their prescribing practice.
Coogan also notes if the drugs do boost the risk of ductal cancer in-situ, avoiding CCBs could be a "major" modifiable risk for breast cancer.
If you are taking a calcium channel blocker for blood pressure, speak with your doctor about the findings. Examples of the medications include nifedipine, amlodipine (Norvasc) and diltiazem. Sometimes the drugs are also prescribed for migraine headache and Reynaud’s disease because they dilate the arteries. Physicians also prescribe the medications to reduce the workload of the heart for people with coronary artery disease who are prone to chest pain or angina.
The finding is not the first to link calcium channel blockers to risk of breast cancer. For now, we don't know if the drugs do or do not cause cancer of the breast. The best advice for women is to keep up with your breast cancer screening until more studies are done. Of course, if the finding is true, it wouldn't be the first time a medication side effect has been discovered years after it has been on the market.