[Clinicopathological features, prognosis and influence in the adjuvant treatment of the risk recurrence groups determined by the 21 gene expression profile, Oncotype Dx®, in early breast cancer]. / Características clinicopatológicas, pronóstico e influencia en el tratamiento adyuvante en los grupos de riesgo de recurrencia determinados por el perfil de expresión de 21 genes, Oncotype Dx®, en cáncer de mama temprano.

BACKGROUND: Adjuvant chemotherapy (ACT) reduces recurrence and mortality in breast cancer (BC); however, not all patients require ACT. Oncotype Dx® (ODX) explores the expression of 21 genes and the risk of recurrence BC. OBJECTIVES: To determine the clinicopathologic characteristics, prognosis, and the prescription for ACT in early BC according to ODX risk groups. METHODS: 36 patients with resected stage I-IIA BC, axillary lymph node-negative or 1-3+, hormonal receptor (HR)-positive, HER2 negative. Three groups were designed by ODX: low (LG), medium (MG) and high-risk groups (HG). RESULTS: LG 23 patients (63.9%), MG eight (22.2%) and HG five (13.9%). We detected high expression of Ki-67 in MG and HG in relation to LG, 21.1 and 32.5 versus 10.1%, respectively (p = 0.007) and lower ER-positive, 85.3, 85.4 and 56.9%, respectively (p = 0.005). Recurrence score: LG 12 (0-18), MG 23 (19-27) and HG 47 (36-57); p < 0.000. Pre-ODX, we planned ACT in 21/36 patients (58.3%) and post-ODX only 9/36 patients (25%) received it. No recurrences or deaths were observed in all groups. CONCLUSIONS: In early BC, 64% have low recurrence risk. High-risk cases presented elevated Ki-67 and lower ER expression. ODX modifies the therapeutic recommendation in 57.2% of cases.