A new observational study raises the possibility that calcium-channel blockers (CCBs) may be associated with a higher risk for breast cancer. Although previous studies examining this relationship have failed to turn up convincing evidence of a link, the authors of a paper published in JAMA Internal Medicine state that their study is the first to look at long-term use of CCBs in a contemporary population.`
Christopher Li and colleagues analyzed data from women in the Seattle area, including 880 women with invasive ductal breast cancer, 1,027 with invasive lobular breast cancer, and 1,027 controls with no cancer. They found that women taking other antihypertensive drugs, including diuretics, beta-blockers, and angiotensin II antagonists, had no increased risk for breast cancer. But women taking CCBs had significantly elevated risk for ductal breast cancer (OR 2.4, CI 1.2-4.9, p=0.04) and lobular breast cancer (OR 2.6, CI 1.3-5.3, p=0.01). The results were consistent for different types of CCBs.
In an accompanying editorial, Patricia Coogan writes that the study “provides valid evidence supporting the hypothesis that long-term CCB use increases the risk of breast cancer.”