Use of Antihypertensive Medications Not Associated with Risk of Contralateral Breast Cancer among Women Diagnosed with Estrogen Receptor-Positive Invasive Breast Cancer.

BACKGROUND Antihypertensive medications are widely used among adults in the United States, and there is some evidence that certain classes may affect the risk of adverse breast cancer outcomes, but their impact on risk of second primary contralateral breast cancer (CBC) is unclear. METHODS We used data from a population-based nested case-control study consisting of 359 women diagnosed with both a first primary breast cancer and a second primary CBC and 691 control women diagnosed with only a single breast cancer and individually matched to cases. Multivariate conditional logistic regression was used to estimate ORs and 95% confidence intervals for risks associated with ever, recency, and duration of use for various antihypertensive medications. RESULTS No class of antihypertensive, including calcium channel blockers, β-blockers, angiotensin-converting enzyme (ACE) inhibitors, and diuretics, was associated with risk of second primary CBC. These results did not change materially in a sensitivity analysis restricted to women with a history of hypertension. CONCLUSION Our findings do not support associations between use of various antihypertensives and CBC risk among women with estrogen receptor-positive breast cancer. IMPACT The present study adds evidence to support the safety of commonly used antihypertensive medications among breast cancer survivors with respect to risk of second primary CBC.