Swedish Study Indicates No Increased Risk of Breast Cancer With 5 Years of Continuous Exposure to Calcium Channel Blockers
A recently reported U.S. population-based case-control study in women aged 55 to 74 years indicated that current use of calcium channel blockers for ≥ 10 years was associated with increased risk of ductal breast cancer (odds ratio [OR] = 2.4) and lobular breast cancer. In a Swedish case-control study reported in a letter to JAMA Internal Medicine, Bergman et al found no increase in risk of breast cancer with continuous calcium channel blocker exposure of 5 years.
No Increase Risk
The study included 3,461 women in the Swedish Cancer Registry aged 55 to 74 years who received a diagnosis of breast cancer for the first time in 2011 and five age-matched women controls per case (n = 17,915) selected from the Swedish Population Registry.
Continuous use of calcium channel blockers from 2006 through 2010 was identified in 4.5% of cases and 4.4% of controls. In analysis adjusted for age, educational level, location of residence, and history of malignant or benign tumors at sites other than the breast, continuous use of calcium channel blockers from 2006 through 2010 was not associated with increased risk of breast cancer vs no continuous use (OR = 1.1, 95% confidence interval [CI] = 0.9–1.3). No trend for risk over time was observed, with no increases in risk being found for 1 (OR = 0.9, 95% CI = 0.7–1.3), 2 (OR = 1.1, 95% CI = 0.8–1.5), 3 (OR = 1.0, 95% CI = 0.7–1.5), or 4 years (OR = 1.1, 95% CI = 0.8–1.6) of continuous use.
The investigators concluded: “The results showed that 5 years of exposure to [calcium channel blockers] did not significantly increase the odds of developing breast cancer (OR, 1.1), which is similar to the effect after 5 to 9.9 years in the [U.S.] study…. However, because [the U.S. study] showed that long-term use (≥ 10 years) of [calcium channel blockers] may increase the odds of developing breast cancer, the Swedish National Board of Health and Welfare intends to continuously monitor the incidence of breast cancer in relationship to the use of [calcium channel blockers].”
Gudrun Jonasdottir Bergman, PhD, of the National Board of Health and Welfare in Sweden, is the corresponding author for the JAMA Internal Medicine letter.
The authors reported no conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
