(RxWiki News) Millions of people rely on calcium channel blockers to control their blood pressure. They are among the most widely prescribed medications in the US. New research suggests that long-term use of these medications may impact cancer risks.
According to this new study, women who took channel blockers for ten or more years had increased breast cancer risks.
None of the other classes of medications used to treat hypertension (high blood pressure) had the same impact.
This was an observational study that looked at trends and didn’t report that channel blockers cause breast cancer — only that years of use may be associated with higher risks for the disease.
"Ask your pharmacist about the long-term risks of your medications."
Christopher I. Li, MD, PhD, of the Fred Hutchinson Cancer Research Center in Seattle, and colleagues conducted this research.
The purpose of this study was to determine any association between hypertension medications (antihypertensive agents) and invasive ductal carcinoma and invasive lobular carcinoma, the two most common forms of breast cancer.
"Calcium channel blockers are prescribed for a number of reasons," Sarah Samaan, MD, FAAC, board certified cardiologist at Legacy Heart Center at the Baylor Heart Hospital, told dailyRx News. “First, they are very effective at treating hypertension. By keeping blood pressure in the normal range, we can prevent heart attacks, strokes, and kidney failure.”
The researchers also looked at other antihypertensive medications. Diuretics help get rid of excess salt and water in the body. Beta blockers reduce the heart’s workload to lower blood pressure. Angiotensin II receptor blockers (ARBs) and angiotensin converting enzyme (ACE) inhibitors both work to reduce blood pressure by relaxing or dilating the blood vessels.
Women aged 55 to 74 from the Seattle-Puget Sound area participated in this study. A total of 880 study members had invasive ductal breast cancer, 1,027 women had invasive lobular breast cancer and 856 participants were cancer-free.
The women had been diagnosed with breast cancer between 2000 and 2008.
The researchers learned that women who had been using calcium channel blockers for 10 or more years had a 240 percent higher risk of developing ductal breast cancer and a 260 percent higher risk of lobular breast cancer than did women not taking the medications.
These results did not vary by type of calcium channel blocker used.
Increased breast cancer risks were not seen among women who used other forms of antihypertensive medications, including diuretics, ACE inhibitors, beta blockers or ARBs.
Examples of calcium channel blockers include:
- amlodipine (Norvasc)
- diltiazem (Cardizem CD, Cardizem LA, Cartia XT, Dilacor XR, Dilt-CD, Dilt-XR, Diltia XT, Diltzac, Matzim LA, Taztia XT, Tiazac)
- felodipine (Plendil)
- isradipine (DynaCirc CR)
- nicardipine (Cardene SR)
- nifedipine (Procardia, Procardia XL, Adalat CC)
- nisoldipine (Sular)
- verapamil (Calan, Verelan, Covera-HS)
“The finding that calcium channel blockers may raise breast cancer risk is disturbing. Although women are six times more likely to die of heart disease than of breast cancer, breast cancer remains a devastating and life-changing diagnosis,” said Dr. Samaan, who was not involved in this study.
“The message to doctors is to consider other options, such as beta blockers, ACE inhibitors, ARB drugs, or diuretics, before turning to calcium channel blockers. If a calcium channel blocker is the best option, it's especially important to undergo regular breast cancer screening. “
“It is equally important,” she continued, “that women (and men) understand that many cases of hypertension are preventable by choosing a healthy diet, exercising regularly, and maintaining a healthy body weight.”
Dr. Samaan added, “Avoiding excessive amounts of salt and alcohol, and getting adequate restful sleep will also help to keep the blood pressure in a normal range. By taking these steps, we can avoid exposure to many pharmaceuticals and also naturally lower our risk for cardiovascular disease and cancer.”
Findings from this study were published August in 5 in JAMA Internal Medicine.
This study was funded by the National Cancer Institute and the US Department of Defense funded the study. No conflicts of interest were disclosed.