Women taking the widely-prescribed blood pressure medications known as beta-blockers when they are diagnosed with breast cancer appear to have a significantly reduced risk for the cancer spreading, or metastasizing. The new study also reported that these women were much less likely to die from breast cancer than women who did not take the medication.

The research team, based at Queen's Medical Centre in Nottingham, England, says that their study is the first ever to look at the relationship between beta-blockers and the spread of cancer. The study was presented last month at the European Cancer Organisation (ECCO)’s European Breast Cancer Conference in Barcelona, Spain.

The team found that the women who were taking beta-blockers had a 71% reduced risk of dying from breast cancer, and a 57% lower risk of developing a second type of cancer.

Des Powe and his colleagues followed 466 breast cancer patients, 92 of whom were on some sort of blood pressure medication. Of these, about half were taking beta-blockers when they were diagnosed with breast cancer. The team found that the women who were taking beta-blockers had a 71% reduced risk of dying from breast cancer, and a 57% lower risk of developing a second type of cancer. These numbers are in relation to women who were either taking a different kind of blood pressure medication or who weren’t taking any kind of blood pressure medication at all. This suggests that the differences seen were actually due to the action of the beta-blocker itself, rather than to the effect of lower blood pressure.

Powe explains that beta- blocker drugs compete with stress hormones and bind, at a cellular level, to the same target receptors as those hormones. But unlike stress hormones, beta-blocker drugs do not activate cancer cells. In other words, blocking the stress hormones may block the ability of the cancer to spread, because cancer cells depend on the presence of these hormones to do so.

Powe says that more research will be needed to assess proper dosing and potential side effects and whether beta-blockers should be given as a supplement to existing breast cancer treatment. Still, he and his colleagues are encouraged by these early results.