Endocrine therapy for hormone treatment-naïve advanced breast cancer

- Few patients with advanced or metastatic breast cancer are endocrine therapy-naïve.
- There is a paucity of clinical studies in endocrine therapy-naïve patients.
- Evidence for efficacy of endocrine therapy in this patient population was reviewed.
- First-line treatment effects are consistent in patients with or without prior endocrine therapy.

A proportion of patients with hormone receptor-positive locally advanced or metastatic breast cancer will not have received prior endocrine therapy. However, there are limited clinical data specifically in these patients. We conducted a review of randomized phase II and III clinical studies of anastrozole, letrozole, exemestane, palbociclib, and fulvestrant to determine the evidence base supporting use of specific endocrine therapies in this patient population. From our findings, there is a paucity of clinical studies in patients with endocrine therapy-naïve disease; however, it appears that first-line treatment effects are consistent between patients who have and have not received prior endocrine treatment.