Breast cancer association with blood pressure drug

Date: Aug-07-2013Postmenopausal women who take a class of medicine for high blood pressure may be at a greater risk for developing breast cancer, according to a recent study by Fred Hutchinson Cancer Research Center scientists.

The study, published in the Journal of the American Medical Association, is the first of its kind to analyze long-term use of the antihypertensive drugs known as calcium-channel blockers and to associate their use to a risk of breast cancer.

The researchers note it has been previously theorized that this type of drug could increase the risk of cancer because they suppress cell death, a normal part of a cell's life.

The team of researchers, led by Dr. Christopher Li, interviewed 1,763 people from the Puget Sound region of Washington state. The participants were all between ages 55-74 years, 880 of whom had invasive ductal cancer, 1,027 had invasive lobular cancer, and 856 were cancer-free.

In the US, about 70% of all breast cancers are invasive ductal carcinomas, while about 20% are invasive lobular carcinomas, the researchers say.

Calcium-channel blockers and cancer risk

Results show that women who took calcium-channel blockers for 10 years or more had a risk for both ductal and lobular cancer that was 2.5 times higher than those who never used calcium-channel blockers or those who used other forms of antihypertensive drug.

Long-term use of other forms of antihypertensive drugs, such as diuretics, beta blockers and angiotensin-receptor blockers, were not linked to an increased breast cancer risk in the study.

Antihypertensives are the most-prescribed drugs in the US, with the researchers citing over 678 million prescriptions filled in 2010, and nearly 98 million being for calcium-channel blockers.

Dr. Li says:

"Because hypertension is a chronic condition, most people with high blood pressure use antihypertensive drugs chronically and will often stay on the same regimen for long periods of time.

Characterizing their potential associations with the most common cancer in women is an important clinical and public health issue, particularly with the increasing availability of alternative options to manage hypertension."

Although many people use high blood pressure drugs, often for long periods of time, the evidence linking use of antihypertensives to breast cancer has been inconsistent.

The study's authors cite two studies, one from 1996 and one from 1997, that showed links between the drugs and breast cancer. But because larger subsequent studies failed to confirm the links, the researchers put their hypothesis "into hibernation." That is, until now, with Li's study adding weight to the link between the drugs and breast cancer.

While the authors say their findings confirm their hypothesis, they call for more research to fully understand the "underlying biological mechanisms potentially responsible for the added risk."

Written by Marie Ellis

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