Relationship between bisphosphonate use and risks of recurrence and mortality among hormone receptor-positive and triple-negative breast cancer patients.

BACKGROUND

Bisphosphonates (BPs) are routinely used as an adjuvant therapy for breast cancer to reduce the risk of bone recurrences given their anti-resorptive effects on bones and antitumor characteristics. However, there remains limited evidence regarding their utility across different subtypes.

METHODS

In this population-based cohort study, the authors assessed the effects of pre- and post-diagnostic BP use on recurrence, any second breast cancer event, all-cause mortality (ACM), and breast cancer-specific mortality (BCSM) using multivariable-adjusted Cox proportional hazards models among hormone receptor-positive (HR+) and triple-negative breast cancer (TNBC) participants.

RESULTS

This study enrolled 2260 HR+ and 1436 TNBC participants. The median age and follow-up time to death was 51 and 52 years old and 168.3 and 147 months in the two subtypes, respectively. Post-diagnostic BP use for at least 1 year was protective for ACM (hazard ratio [HR], 0.67; 95% confidence interval [CI], 0.49-0.93) and BCSM (HR, 0.54; 95% CI, 0.33-0.89) compared to never users in HR+ cases. Among participants who initiated BP after diagnosis only, a lower point estimates on the clinical outcomes were observed across both subtypes, reaching statistical significance for BCSM (HR, 0.62; 95% CI, 0.39-0.98) in HR+ cases. Among TNBC cases who continued BP use post-diagnosis, increased risks of recurrence (HR, 3.43; 95% CI, 1.67-7.07) and BCSM (HR, 2.54; 95% CI, 1.24-5.19) were observed.

CONCLUSIONS

Although this study confirmed the protective effects of post-diagnostic BP use on risks of mortality among HR+ cases, further studies are required to prove the effects of post-diagnostic BP use among TNBC participants.