A study suggests that older women who have taken calcium-channel blockers to treat high blood pressure for 10 years or more have a higher risk of breast cancer.
The research was published online on Aug. 5, 2013 by JAMA Internal Medicine. Read the abstract of “Use of Antihypertensive Medications and Breast Cancer Risk Among Women Aged 55 to 74 Years.”
Calcium-channel blockers are a common type of high blood pressure medicine. (Doctors call high blood pressure “hypertension.”) Medicines to treat high blood pressure are the most commonly prescribed types of medicines in the United States. In 2010, about 98 million prescriptions for calcium-channel blockers were filled. Other types of high blood pressure medicines are ACE inhibitors, beta blockers, and diuretics.
Because high blood pressure is a chronic condition -- meaning it lasts for a long time -- most people who take medicine to treat it take the medicine for a long time.
Earlier studies have looked for a possible link between high blood pressure medicines and breast cancer risk, but the studies were small and the results were mixed.
In this study, researchers interviewed 2,763 women in the three counties around the city of Seattle:
- 880 women were diagnosed with invasive ductal breast cancer
- 1,027 women were diagnosed with invasive lobular breast cancer
- 856 weren’t diagnosed with breast cancer
All the women were postmenopausal and between the ages of 55 and 74. Women that had been diagnosed with breast cancer were diagnosed between January 2000 and December 2008.
Invasive ductal breast cancer is cancer that starts in the milk ducts. Invasive lobular breast cancer is cancer that starts in the milk-producing lobules, which empty out into the ducts that carry milk to the nipple.
The researchers asked the women about their history of high blood pressure and heart disease, as well as risk factors for cancer, such as family history, smoking and alcohol use, and obesity. The researchers also asked the women about any high blood pressure medicines they took, including when they started and stopped, the name of the medicine, and the dose.
The researchers found that the risk of breast cancer -- either invasive ductal or invasive lobular -- was more than doubled in women who took calcium-channel blockers for 10 years or longer. The risk was the same for all types of calcium-channel blockers, including short-acting and long-acting.
Other types of high blood pressure medicine, including diuretics, beta blockers, and ACE inhibitors, WEREN’T linked to an increase in breast cancer risk.
While the results of this study are troubling, it’s important to know three things:
- The women had to remember which high blood pressure medicines they took and how long they took the medicines for; it could be that some women misremembered what they took and for how long.
- High blood pressure medicines that aren’t calcium-channel blockers, including diuretics, beta blockers, and ACE inhibitors, weren’t linked to a higher risk of breast cancer.
- While this study suggests that calcium-channel blockers are associated with a higher risk of breast cancer, more research is necessary before any recommendations are changed.
- This study doesn’t offer clear evidence that every woman should stop taking calcium-channel blockers.
If you’re a postmenopausal woman who takes high blood pressure medicine, it’s a good idea to talk to your doctor about this study. Find out what type of high blood pressure medicine you’re taking. If it’s a calcium-channel blocker, you might want to ask your doctor if you should take a different type of high blood pressure medicine, maybe a beta blocker or an ACE inhibitor. Ask your doctor about the risks and benefits associated with each medicine you’re considering.
If a calcium-channel blocker is the best high blood pressure medicine for your unique situation, try to do everything you can in other areas of your life to minimize the breast cancer risk factors you can control, including:
- eating a healthy diet that’s low in processed foods and sugar
- avoiding alcohol
- maintaining a healthy weight
- exercising daily
- not smoking
All of these factors also affect heart health, so sticking to them also may help control high blood pressure.
You can learn much more about breast cancer risk and other steps you can take to minimize that risk in the Breastcancer.org Lower Your Risk section.