Study: Some Blood Pressure Drugs May Increase Breast Cancer Risks

blood_pressure_medication_cancer_linkUse of a type of blood pressure medications might increase risks for developing breast cancer, according to an emerging study.

The study found the first possible connection between long-term use—more than 10 years—of calcium channel blockers and increased breast cancer risks when compared to women who never took those types of medications or who used other blood pressure drugs, according to Bloomberg News. Risks increased by 2.5-fold. The research appears in JAMA Internal Medicine.

Norvasc (amlodipine), manufactured by Pfizer Inc. is a type of calcium-channel blockers prescribed for high blood pressure. Other channel blockers include Cardizem LA and Tiazac (diltiazem); DynaCirc CR (isradipine); Cardene SR (nicardipine ); Procardia, Procardia XL, and Adalat CC (nifedipine); Sular (nisoldipine); and Calan, Verelan, and Covera-PM (verapamil), according to HealthDay News.

Additional research is needed to mimic the findings and understand why this class of blood pressure medications may present increased breast cancer risks, said Christopher Li, the study’s lead author.  “While this is an intriguing finding, much more work still needs to be done,” Li, head of the Translational Research Program at the Fred Hutchinson Cancer Research Center in Seattle, wrote in an email. “While we appreciate that these results may cause concern for women currently using these medications, we do not think that they should change current clinical practice because they require confirmation and because of the importance of managing hypertension effectively.”

Drugs like Norvasc lower blood pressure by relaxing blood vessels and preventing calcium from entering the cells, Bloomberg News explained. For this study, 1,960 women diagnosed with breast cancer and 891 women who were free of the disease, were interviewed to determine what blood pressure treatments they were using and for how long they had been using those treatments.

According to Li, it remains unclear why calcium-channel blockers may raise the likelihood of developing breast cancer, noting that the findings were only applicable to older women and the study was unable to evaluate the risk in women who stopped using the drugs, according to Bloomberg News.

“We looked at these drugs because people who use them to manage their blood pressure are usually on them for the rest of their lives,” Li, of the Fred Hutchinson Cancer Research Center in Seattle, said, according to HealthDay News. “There has been some evidence suggesting that some of these antihypertensives may be related to breast cancer risk.”

Li cautioned that the findings reveal a connection between calcium channel blockers and breast cancer, but the data do not prove the drugs cause breast cancer. “We need to see confirmation of these results before we make any recommendation for women to change what they are using,” Li said, according to HealthDay News.

More than 232,000 women will be diagnosed with breast cancer in the United States, this year along; more than 39,600 will die, according to the National Cancer Institute, wrote Bloomberg News. The National Cancer Institute funded the study.

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