Beta-1 selective blockers linked to breast cancer risk

Women using beta-1 selective blockers may be at increased risk of developing breast cancer, with the association showing a dose-response pattern, according to a study.

The study drew data from Swedish national registers and included female hypertensive patients who were prescribed nonselective beta-blockers (propranolol) and beta-1 selective blockers (metoprolol, atenolol, bisoprolol), along with propensity score-matched nonusers.

Researchers used the cumulative defined daily dose to examine whether there was a dose-response association. They also performed a test of interaction between beta-blocker use and other blood pressure-lowering medications.

Hypertensive patients on beta-1 selective blockers had a two- to threefold higher risk of developing breast cancer compared with nonusers. The corresponding hazard ratios were 2.39 (95 percent confidence interval [CI], 1.95–2.94) with metoprolol, 2.31 (95 percent CI, 1.46–3.64) with atenolol, and 3.02 (95 percent CI, 2.09–4.36) with bisoprolol. The risk was dose-dependent in all associations (p_trend<0.0001).

There was no risk increase noted for the nonselective beta-blocker. However, among users of agents acting on the renin–angiotensin system, those who used propranolol had a heightened breast cancer risk. Modification of agents acting on the renin–angiotensin system on breast cancer risk was also seen among atenolol users.

The findings highlight the importance of breast cancer surveillance for hypertensive female patients using beta-1 selective blockers.