Fall 2013

Does blood pressure medication increase breast cancer risk?

Dr. Christopher Li explains the emerging link between certain antihypertensive drugs and breast cancer.

by Andy Koopmans




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 Dr. Christopher Li. The study is the first to observe that long-term use of a class of antihypertensive drugs known as calcium-channel blockers are associated with breast cancer risk.

Antihypertensive drugs are the most frequently prescribed medications in the United States, with more than 678 million prescriptions filled in 2010, nearly 98 million of which were for calcium-channel blockers.

Dr. Christopher Li
Dr. Christopher Li
Despite widespread and often long-term use of these drugs, studies and evidence linking them to breast cancer have been sparse and inconsistent.

The Fred Hutch team's findings were published in JAMA Internal Medicine. The study was covered by NBC's "Today Show," CBS News and other major media outlets, and generated numerous questions for Li.

Q: How can women tell if their antihypertensive drug is a potential risk?

A: Our study only included women 55 to 74 years of age and so we do not know if these results also apply to younger women. That said, the primary reason people use calcium-channel blockers is for hypertension, which is much more common among older than younger people.

Q: What alternatives are there to calcium-blocking antihypertensive drugs?

A: There are multiple classes of medications that are used to manage hypertension including diuretics, ACE inhibitors and beta blockers. However, the results of this study require confirmation before women taking calcium-channel blockers should consider switching to a different medication because of concern related to a possible association with breast cancer.

Q: Does being on a combination of antihypertensive drugs, including calcium-channel blockers, pose a greater breast cancer risk than being only on calcium-channel blockers?

A: We did not find any difference in cancer risk between women using calcium channel blockers alone or in combination.

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Q: Are there any studies that correlate calcium-channel blockers with increased cancer risks for men as well?

A: We are not aware of any consistently observed relationships between calcium-channel blocker use and cancer in men.

Q: Did the study take into account other cancer risk factors that could have affected these women?

A: Yes, our analyses incorporated the potential impact of multiple other breast cancer risk factors that could have influenced our results such as alcohol use, body weight, family history of breast cancer and hormone use. Our results were adjusted for those factors.

Q: Should women stop taking calcium-channel blockers?

A: We do not think that the results of this study should alter current clinical practice in any way. While these results are intriguing, they require confirmation before any clinical recommendations can be made..

Q: Should women who have been on calcium-channel blocker antihypertensive for a long time get screened for cancer?

A: The results of this study should not influence current guidelines for cancer screening. Women should continue to follow appropriate breast cancer screening guidelines regardless of whether they take calcium channel blockers.

Q: What are the underlying causes for the increased cancer risk with these drugs?

A: The biology underlying this potential relationship is not well understood. There are several potential hypotheses, but none have yet been substantiated.

Q: Who funded your research?

A: This study was funded by the National Cancer Institute and the Department of Defense Breast Cancer Research Program.

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