According to the findings of a new study, long-term use of high blood pressure drugs, called calcium-channel blockers, may raise the risk of breast cancer in older women.
The study was conducted by the researchers at the Fred Hutchinson Cancer Research Center.
For the purpose of the study, researchers looked at 2,763 women between ages 55 and 74, inhabitants of the Seattle-Puget Sound area. Two-thirds of the women were diagnosed with breast cancer between 2000 and 2008.
While 905 women were diagnosed with ductal breast cancer, 1,055 women had lobular breast cancer. 891 women without cancer formed the control group.
Nearly 40 percent participants in each group were taking medicines to correct high blood pressure.
Researchers found that women who used calcium-channel blockers for 10 years or more were 2.4 times more likely to be diagnosed with ductal breast cancer and 2.6 times more likely to be diagnosed with lobular breast cancer.
Ductal carcinoma is the most common type of breast cancer. It forms in the lining of the tubes that carry milk from the lobules to the nipple. However, lobular carcinoma or lobular breast cancer begins in the milk glands.
“This is the first study to observe that long-term current use of calcium-channel blockers in particular are associated with breast cancer risk,” study’s lead researcher, Dr. Christopher I. Li, an epidemiologist at the Fred Hutchinson Cancer Research Center in Seattle said.
Calcium channel blockers prevent clogging of blood vessels by stopping calcium from entering cells of the heart and blood vessel walls. The phenomenon in turn clears and widens the blood vessels, lowering the blood pressure.
While the researchers are not clear about the link between the use of calcium channel blockers and breast cancer risk, they feel the drugs may prevent programmed cell death or apoptosis, linked to development of cancer cells.
Interestingly, use of other class of blood pressure drugs like the alpha-blockers, diuretics, beta-blockers, ACE Inhibitors, Angiotensin II receptor blockers (ARBs) and vasodilators did not soar the risk of breast cancer in older women, researchers averred.
“Because hypertension is a chronic condition, most people with high blood pressure use antihypertensive drugs chronically and will often stay on the same regimen for long periods of time,” said Li. “Characterizing their potential associations with the most common cancer in women is an important clinical and public health issue, particularly with the increasing availability of alternative options to manage hypertension.”
The findings of the study are reported Aug. 5 in JAMA Internal Medicine .