Q&A with Dr. Christopher Li regarding high blood pressure medication and breast cancer risk
Dr. Christopher Li and colleagues in the Public Health Sciences Division of Fred Hutchinson Cancer Research Center recently published a paper in JAMA Internal Medicine about a study that found an association between the use of certain types of high blood pressure medication and an elevated risk of breast cancer in postmenopausal women.
Their findings showed that women between the ages of 55 and 74 who had used a certain class of antihypertensive drugs, known as calcium-channel blockers, for 10 years or longer had approximately two-and-a-half-times higher risk of invasive ductal and invasive lobular breast cancers compared to those who have never used antihypertensives and users of other forms of high blood pressure medication.
In contrast, the study found that use of other classes of antihypertensive drugs, including beta-blockers and angiotensin II antagonists, were not associated with an increased risk of breast cancer, even when used for long durations. Read the news release here.
Below Li has responded to several frequently asked questions about the findings.
How can women tell if the antihypertensive drug they are on is a potential risk?
The types of antihypertensives that we found to be possibly related to breast cancer risk are called calcium-channel blockers. There are several types of calcium-channel blockers that are widely used and they go by different generic and brand names. So, the easiest way to check would be to look at the package insert or look up individual drugs online to determine if it is a calcium-channel blocker.
Is the higher risk of breast cancer associated only with older/postmenopausal women or should younger women also be concerned?
Our study only included women 55 to74 years of age and so we do not know if these results also apply to younger women. This said, the primary reason people use calcium-channel blockers is for hypertension, which is much more common among older than younger people.
What alternatives are there to calcium-blocking antihypertensive drugs?
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.
Are women who are on a combination of antihypertensive drugs, including calcium-channel blockers, at greater risk for breast cancer as well as those on calcium-channel blocking drugs alone?
We did not find any difference in cancer risk between women using calcium channel blockers alone or in combination.
Are there any studies that correlate calcium-channel blockers with increased cancer risks for men as well?
We are not aware of any consistently observed relationships between calcium-channel blocker use and cancer in men.
Did the study take into account other cancer risk factors that could have affected the women studied?
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 that influenced the relationships observed.
Should women who have been on calcium-channel blocker antihypertensives fewer than 10 years stop taking them?
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.
Should women who have been on calcium-channel blocker antihypertensives for a long time get screened for cancer?
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.
What are the underlying causes for the increased cancer risk with these drugs?
The biology underlying this potential relationship is not well understood. There are several potential hypotheses, but none have yet been substantiated.
Who funded your research study?
This study was funded by the National Cancer Institute and the Department of Defense Breast Cancer Research Program.