Beta-blocker use and breast cancer outcomes: a meta-analysis.

Purpose: Beta blockers (BBs) are commonly used cardiovascular medications, and their association with breast cancer outcomes has been examined in several previous observational studies and meta-analyses. In this study, an updated meta-analysis was undertaken to ascertain the association between BBs and both breast cancer death (BCD) and breast cancer recurrence (BCR).

Methods: Articles were sourced from various databases up until the 14th of August 2023. Effect estimates were pooled using the random effects model, and the Higgins I statistic was computed to ascertain heterogeneity. Subgroup analyses were conducted by the potential for immortal time bias (ITB), the exposure period (prediagnosis vs postdiagnosis), and type of BB (selective vs non-selective). Publication bias was assessed using funnel plots and Egger's regression tests.

Results: Twenty-four studies were included. Pooled results showed that there was no statistically significant association between BB use and both BCD (19 studies, hazard ratio = 0.90, 95% CI 0.78-1.04) and BCR (16 studies, HR = 0.87, 95% CI 0.71-1.08). After removing studies with ITB, the associations were attenuated towards the null. There was no effect modification for either outcome when stratifying by the exposure period or type of BB. There was clear evidence of publication bias for both outcomes.

Conclusion: In this meta-analysis, we found no evidence of an association between BB use and both BCD and BCR. Removing studies with ITB attenuated the associations towards the null, but there was no effect modification by the exposure period or type of BB.