Beta-adrenergic blocking drugs in breast cancer: a perspective review

The purpose of this review is to present the preclinical, epidemiological and clinical data relevant to the association between beta-blockers and breast cancer progression. Preclinical studies have shown that beta-adrenergic receptor (beta-AR) signalling can inhibit multiple cellular processes involved in breast cancer progression and metastasis, including extracellular matrix invasion, expression of inflammatory and chemotactic cytokines, angiogenesis and tumour immune responses. This has led to the hypothesis that the commonly prescribed class of beta-AR antagonist drugs (beta-blockers) may favourably impact cancer progression. A number of recent pharmacoepidemiological studies have examined the association between beta-blocker exposure and breast cancer progression. The results from these studies have suggested a potential role for targeting the beta-AR pathway in breast cancer patients. Larger observational studies are, however, required to confirm these results. Questions regarding the type of beta-blocker, predictive biomarkers or tumour characteristics, appropriate treatment paradigms and, most importantly, efficacy must also be answered in randomized clinical studies before beta-blockers can be considered a therapeutic option for patients with breast cancer.