Associations of Commonly Used Concomitant Medications With Survival and Adverse Event Outcomes in Breast Cancer

The impact of commonly used non-cancer medications on breast cancer outcomes remains underexplored in large datasets.

To evaluate the associations between commonly used non-cancer medications and survival as well as adverse events in patients with breast cancer.

Individual participant data from 19 breast cancer clinical trials (n = 23,211) were pooled. Cox proportional hazards models and logistic regression analyses were used to assess associations between medication use and overall survival, progression-free survival and grade ≥ 3 adverse events. Analyses were adjusted for demographic, cancer and comorbidity factors.

Proton pump inhibitor use was associated with poorer overall survival (HR 1.19, 95% CI: 1.08-1.30), progression-free survival (HR 1.11, 95% CI: 1.02-1.21) and an increased risk of grade ≥ 3 adverse events (OR 1.36, 95% CI: 1.21-1.53). Beta-blockers, ACE inhibitors/ARBs and calcium channel blockers were linked with higher adverse event rates but showed no significant impact on survival. Statins and metformin demonstrated no significant associations with either survival or adverse events.

These findings emphasise the need for careful management of concomitant medications in breast cancer care and support ongoing research to optimise treatment safety and efficacy.