A Review of Current Literature and Real-World Outcomes With Neoadjuvant Chemotherapy in Hormone Receptor Positive, HER2 Negative Breast Cancer.

Background: Neoadjuvant chemotherapy has been used to downstage locally advanced ER+/HER2- breast cancer with low response rates. The optimal neoadjuvant regimen for this population is unknown.

Patients and methods: Between 2017 and 2022, 192 patients (ages 28-78) with stage II/III ER+/Her2- breast cancer at our institution were evaluated. Patients were divided into 4 groups based on the neoadjuvant chemotherapy regimen used (AC-T, TC, TAC, or other). The responses were categorized as complete (ypT0/is ypN0), partial, no response, or progressive disease.

Results: The choice of neoadjuvant chemotherapy was not predictive of pCR (P = .3864), even among those with more advanced nodal disease. No significant difference was noted in OS or IDFS at 24 or 48 months between the AC-T and TC groups. In the AC-T group (n = 130), 9 patients had a CR (6.98%), while no patients in TC group had a CR. Those who were premenopausal were more likely to achieve pCR compared to those postmenopausal. Race significantly impacted IDFS.

Conclusions: In this single center study, we found no differences in IDFS or OS when comparing neoadjuvant TC to AC-T. The AC-T regimen group had a higher pCR rate of 6.98% compared to 0% in TC regimen group. Further exploration is needed to understand why non-white populations have inferior IDFS.