Abstract PS3-11-03: Pathologic Complete Response and Surgical Outcomes, in a Brazilian Cohort

Abstract Introduction: Neoadjuvant chemotherapy (NACT) is a treatment strategy for locally advanced tumors and even for operable tumors in situations that can determine prognosis, modify adjuvant treatment and reduce surgical intensity. Method: This study evaluated Brazilian patients undergoing NACT from 2013-2023 in a Cancer Center in Brazil, through a retrospective cohort, analyzing the chemotherapy (CT) performed, pathological complete response rate (pCR) and surgical outcomes, the latter particularly in the HER2 positive (+) and Triple Negative (TN) population. Results: A total of 1,626 female patients were included, median age at diagnosis 46. The most frequent tumor subtype was luminal B (38.4%), followed by Her2 + (29.5%, including luminal) and TN (27.4%). Locally advanced tumors (T3-T4) accounted for 53.5% of cases and 67.2% were cN+ (cN1- 45.2%, cN2 -16.1% and cN3- 5.9%). Of the breast surgeries, 33.9% were conservative (BCS), 61.4% mastectomies, 4.7% nipple-sparing. Of the axillary surgeries, 38.0% were sentinel lymph node biopsies (SLNB), 67.1% lymphadenectomies (LA). The pCR occurred in 38.3% of cases, but was higher depending on the treatment modality, as shown in the table 1. The high-volume disease also influenced the pCR: N1 (16.4%) compared to N3 (1.6%, p