High blood pressure is a known risk factor for postmenopausal breast cancer, in addition to increasing the likelihood of stroke and other adverse cardiovascular events. Therefore, while hypertension can in some cases be eliminated through diet and exercise, treatment normally starts with medications (which can be reduced or discontinued once lifestyle changes show evidence of efficacy).

Beta blockers and ACE inhibitors (angiotensin-converting enzyme inhibitors), two classes of drugs used to treat high blood pressure, have been studied fairly extensively with regard to breast cancer. Use of beta blockers appears to reduce breast cancer risk and recurrence. On the other hand, while the evidence is not consistent, use of ACE inhibitors has been linked to increased risk of breast cancer recurrence. Now a new study has reported that long-term use of another class of hypertensive drugs, calcium-channel blockers, is associated with significantly increase risk of breast cancer in postmenopausal women.

Latest research finds calcium-channel blockers might increase breast cancer risk

The study referenced at the beginning of this news article was designed to investigate the relationships between different types of high blood pressure drugs and risks of invasive ductal and lobular breast cancer among postmenopausal women. The study included women aged 55 to 74 years in the Seattle-Puget Sound area of Washington state. A total of 880 participants had ductal breast cancer, 1,027 had lobular breast cancer, and 856 were cancer free and served as controls.

Use of calcium-channel blockers for 10 years or longer was found to be associated with more than double (2.4 times) the risk of ductal breast cancer and lobular breast cancer (2.6 times) than non-use. The type of calcium-channel blocker used (short-acting or long-acting, dihydropyridines or non-dihydropyridines) did not change these relationships significantly. On the other hand, use of diuretics, beta blockers, and angiotensin II antagonists (angiotensin-receptor blockers or ARBs) were not found to be associated with breast cancer risk. The authors comment that while previous studies have suggested a positive association between calcium-channel blocker use and breast cancer, this is the first study to report that long-term use is associated with heightened breast cancer risk. More research is needed to confirm the finding.