Angiotensin-converting enzyme inhibitors, calcium channel blockers, and breast cancer.

Background: The use of angiotensin-converting enzyme (ACE) inhibitors has been linked to a decreased risk of developing cancer, and longer-term use of calcium channel blockers (CCBs) has been associated with an increased risk of developing cancer in general and breast cancer in particular.
Methods: Using data from the General Practice Research Database, we conducted a large case-control analysis. Previous exposure to ACE inhibitors, CCBs, and beta-blockers was compared between 3706 postmenopausal women who were diagnosed with incident breast cancer between 1992 and 1997 and 14155 matched-control women.
Results: Compared with nonusers of antihypertensive drugs, women who used ACE inhibitors (odds ratio [OR], 1.0; 95% confidence interval [CI], 0.7-1.5), CCBs (OR, 0.9; 95% CI, 0.7-1.2), or beta-blockers (OR, 1.0; 95% CI, 0.8-1.2) for 5 or more years were not at an increased or decreased risk of developing breast cancer (adjusted for smoking and body mass index [calculated as weight in kilograms divided by the square of height in meters]). The risk of breast cancer did not differ between users of different ACE inhibitors or different CCBs (dihydropyridines, diltiazem hydrochloride, and verapamil hydrochloride) or between users of short-acting (OR, 1.0; 95% CI, 0.7-1.4) or sustained-release (OR, 1.0; 95% CI, 0.8-1.3) nifedipine preparations.
Conclusion: The findings of this large case-control analysis do not support the hypothesis that longer-term use of ACE inhibitors or CCBs affects the risk of developing breast cancer.