Breast Cancer and High Blood Pressure

A recent study showed that women who had been taking calcium-channel blockers to treat high blood pressure for more than 10 years were 2.5 times more likely to have breast cancer, compared with women who did not use blood pressure medication, or who used other types.  However, it should be cautioned that the study is preliminary and further studies are needed before recommendations are made.  So, continue taking your medications but the findings are interesting, to say the least.
About 1,900 women with breast cancer participated in the study, as well as about 850 women with no cancer who served as the control group.  The researchers didn’t find a link between an increased breast cancer risk and other types of high blood pressure medications, such as beta-blockers or diuretics, according to the study published in the Journal of the American Medical Association.
Medications for treating high blood pressure, called antihypertensives, are the most commonly prescribed drugs in the United States.  An estimated 678 million prescriptions were filled in 2010, including 98 million prescriptions for calcium-channel blockers, the researchers said.
A professor in epidemiology at Boston University noted in an editorial that this is not the first time that the specter of a link between [calcium-channel blockers] and breast cancer risks have risen.
But previous studies had yielded mixed results. They did not have a sufficient number of participants, or did not investigate long-term use of antihypertensives.  The professor said that the study “is a very well-done study and therefore there appears to be a hypothesis that now needs to be confirmed.”  She also said that the study isn’t at a stage where women should be panicking about taking these drugs. The study shows a link, but does not prove a cause-and-effect relationship between the drugs and breast cancer.
Calcium-channel blockers work by slowing the movement of calcium into muscle cells, which dilates blood vessels, reduces the force of the heart’s contractions and slows the heartbeat.  Doctors may consider how the patient responds to different medications, and their other conditions.  There are people who don’t tolerate some of the other classes of medications, and respond well to calcium-channel blockers.
However, if patients are concerned, and because there are several classes of hypertensives, patients can certainly discuss their options with their physician, and look into alternative blood pressure treatments.  Be sure to discuss your concerns with your doctor.
The next step in the current research would be to look at more groups of people who take blood pressure medications, as well as to better understand the underlying mechanism by which the calcium-channel blockers may affect cancer risk, the researchers said.
Antihypertensives only came on the market in the past few decades, so there has not been sufficient number of long-term users of these medications.
We are now getting to the point where we have enough people who’ve been exposed to these medications for long periods of time to evaluate such long-term potential risks.