Response to Induction Neoadjuvant Hormonal Therapy Using Upfront 21-Gene Breast Recurrence Score Assay-Results From the SAFIA Phase III Trial.

Purpose: Luminal, human epidermal growth factor receptor 2-negative breast cancer represents the most common subtype of breast malignancies. Neoadjuvant strategies of operable breast cancer are mostly based on chemotherapy, whereas it is not completely understood which patients might benefit from neoadjuvant hormone therapy (NAHT).

Materials And Methods: The SAFIA trial is a prospective multicenter, international, double-blind, neoadjuvant phase III trial, using upfront 21-gene Oncotype DX Breast Recurrence Score assay (recurrence score [RS] < 31) to select operable luminal human epidermal growth factor receptor 2-negative patients, for induction hormonal therapy HT (fulvestrant 500 mg with or without goserelin) before randomly assigning responding patients to fulvestrant 500 mg (with or without goserelin) plus either palbociclib (cyclin-dependent kinase 4/6 inhibitor) or placebo.