Long-Term Use of Some High Blood Pressure Drugs Associated With Increased Risk of Breast Cancer in Postmenopausal Women
Older women who take certain types of medication to combat high blood pressure may be putting themselves at greater risk for developing breast cancer, according to a new study by a team of Fred Hutchinson Cancer Research Center scientists led by Christopher Li, M.D., Ph.D and funded by the National Cancer Institute. The study is the first to observe that long-term use of a class of antihypertensive drugs known as calcium-channel blockers in particular are associated with breast cancer risk.
The study's key finding was that women currently taking calcium-channel blockers who have used them for 10 years or longer had an approximately two and a half times higher risk of both invasive ductal and invasive lobular cancers compared to those who never used such calcium-channel blockers and compared to users of other forms of antihypertensives. In contrast, the study found that use of other classes of antihypertensive drugs, including diuretics, beta blockers and angiotensin-receptor blockers, were not associated with an increased risk of breast cancer, even when used long term.
Antihypertensive drugs are the most frequently prescribed type of medications in the United States, with more than 678 million prescriptions filled in 2010, nearly 98 million of which were for calcium-channel blockers.
While calcium-channel blockers in particular appear to have an implication for increased cancer risk in cases of long-term use, the drugs have a broad spectrum of physiological effects, and more research will be required to understand the underlying biological mechanisms potentially responsible for the added risk. Calcium-channel blockers function by regulating the influx of calcium into muscle cells, decreasing arterial resistance and heart muscle oxygen demand. Some hypothesize that these drugs may increase cancer risk because they inhibit programmed cell death, or apoptosis, but supporting evidence is lacking.
The above story is based on materials provided by Fred Hutchinson Cancer Research Center.
1. Patricia F. Coogan, ScD1. Calcium-Channel Blockers and Breast Cancer A Hypothesis Revived. JAMA Intern Med., 2013 DOI: 10.1001/jamainternmed.2013.9069
2. Christopher I. Li et al. Use of Antihypertensive Medications and Breast Cancer Risk Among Women Aged 55 to 74 Years. JAMA Intern Med., 2013 DOI:10.1001/jamainternmed.2013.9071