Beta-Blockers Use and Risk of Breast Cancer in Women with Hypertension

Background: The risk of breast cancer among hypertensive patients who use beta-blockers has attracted attention. However, the evidence is inconsistent and investigation of the dose-specific associations for subtypes of beta-blockers is limited. Methods: By incorporating Swedish national registers, breast cancer risk was estimated in women with hypertension who used nonselective beta-blockers and beta-1 selective blockers compared with propensity score–matched nonusers. The cumulative defined daily dose was used to study the dose–response association. Test of interaction between beta-blocker use and other antihypertensive medications was performed. Results: Hypertensive patients taking beta-1 selective blockers (metoprolol, atenolol, bisoprolol) had an increased risk of breast cancer with a HR and 95% confidence interval (CI) of 2.39 (1.95–2.94), 2.31 (1.46–3.64), and 3.02 (2.09–4.36), respectively. All of the observed associations were dose-dependent (Ptrend < 0.0001). No significant association was found for the nonselective beta-blocker (propranolol) except that among users of agents acting on the renin–angiotensin system, those who used propranolol had increased breast cancer risk. Modification of agents acting on the renin–angiotensin system on breast cancer risk was also observed for atenolol. Conclusions: The increased risk of breast cancer associates with the use of beta-1 selective blockers in a dose–response manner. Impact: Breast cancer surveillance is recommended for hypertensive female patients using beta-1 selective blockers.