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Study: Common Blood Pressure Drugs Do Not Increase Risk of Breast Cancer

Findings refute previous study

Women who take a common type of medication to control their blood pressure are not at increased risk of developing breast cancer because of the drug, according to a new study by researchers at the Intermountain Medical Center Heart Institute in Murray, Utah.

The investigators analyzed the records of more than 3,700 women who had no history of breast cancer and who had long-term use of calcium channel blockers (CCBs) to control their blood pressure. The researchers found only a minimal increase in risk in one study and a 50% reduced risk in a second, leading them to recommend the continued use of these important medications to help prevent heart attack and stroke.

Findings from the study were presented November 19 at the 2014 American Heart Association Scientific Sessions in Chicago, Illinois.

CCBs are commonly used to help prevent calcium from entering cells of the heart and blood vessel walls, resulting in lower blood pressure.

“We found no robust data that calcium channel blocker medications increase a person’s risk of breast cancer,” said cardiologist Jeffery L. Anderson, MD. “Given the important role calcium channel blocker medications play in treating heart conditions, we think it’s premature to discontinue their use. At this point, we recommend that patients continue taking these medications to treat their hypertension.”

The investigation was in response to a similar study released last year by the Fred Hutchinson Cancer Research Center in Seattle, Washington. That study suggested that the risk of developing breast cancer was 2.5 times higher for women treated with CCBs. The results of the new study indicated small to no increased risk.

The researchers examined data from more than 3,700 women aged 50 to 70 years with no history of breast cancer in two Intermountain Healthcare databases. For each group, the investigators compared women who were prescribed CCBs with similar women who weren’t prescribed these medications.

In their review of a general-population medical records database, the researchers found that the risk of breast cancer was 1.6 times higher in CCB users, which was significant but much smaller than that reported by the Seattle group.

Moreover, in data collected from patients treated at the Intermountain Cardiac Catheterization Laboratory, a reverse relationship was found –– a 50% reduction in the risk of developing breast cancer for women who used CCBs.

The contrasting results found in these two independent analyses led researchers at the Intermountain Medical Center Heart Institute to conclude that it was likely not the CCBs that caused the changes in breast cancer risk but other factors, such as selection biases.

Source: EurekAlert; November 19, 2014.

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