Abstract P2-16-30: Neoadjuvant therapy outcomes in non metastatic invasive breast carcinomas - Results from a large Brazilian cohort
Authors: Tavares Monique Celeste , Cesca Marcelle G , Oliveira Fernanda A , Andrade Poliana , Fogassa Camilla A , Pirolli Rafaela , Mattos Bruna R , Xerfan Mariana P , Figueiredo Sinara , Campos Fernando AB , Calsavara Vinicius F , Sanches Solange M , Makdissi Fabiana B , Bueno Cynthia A , Sonagli Marina , Canal Marina , Lima Vladmir CC 
Published: March 2020

Introduction: Neoadjuvant chemotherapy in addition to increasing the rate of breast conservation, offers a invaluable opportunity to monitor individual tumor response which may be related to survival outcomes. In view of this, neoadjuvant treatment has been increasingly used.However, several distinct strategies and protocols are employed in this scenario, depending on the histological subtype and local preferences, and there is no clear definition of which one is the best. Most of the published series are from developed countries. Here we describe results of neoadjuvant therapy for non metastaic breast cancer treated in a single Brazilian cancer center.Objective: To evaluate the clinical and pathological characteristics and survival outcomes of breast cancer patients treated with neoadjuvant chemotherapy diagnosed in a single specialized Brazilian institution. Method: This is an observational, retrospective cohort, which included patients diagnosed with invasive breast cancer (stage I to III) submitted to neoadjuvant chemotherapy between January 2007 and December 2018.Results: We evaluated 685 patients with a median age of 46 years, 23.9% were younger than 40 years of age, 64.2% were premenopausal, 24% had a mutation in the BRCA1/2 gene and 70% were treated in the private.Regarding staging, 2.2% had stage I disease, 33.9% stage II, and 63.9% stage III. Approximately 95% of patients received anthracycline-containing regimens. Among patients with ERBB2+ tumors, 97.1% received an anthracycline regimen and 30.3% received double anti-HER2 blockade. Eleven percent of patients with triple-negative triple tumors received carboplatin, and only 0.5% of the hormone receptor positive patients received neoadjuvant hormone therapy. Forty percent of the patients demonstrated complete clinical response and only 30% of thenderwent conservative surgery. Thirty-seven percent had complete pathological response (RCB-0), 13.1% had minimal residual disease (RCB-1,) 40% had moderate to extensive residual disease (RCB-2 and RCB-3), and 0, 8% presented disease progression. The RCB-0 rate was 45.7% for AC dense dose and 31.9% AC for conventional dose (p=0.001). Regardless of hormonal status, in the subgroup with ERBB2 + tumors, the rate of RCB-0 was 61% for those who received HER2 double-blockade versus 55.1% for those who received anti-HER2 monotherapy (p=0.049). Nineteen percent of the patients progressed during the follow-up, with 17% having locoregional progression. In the last follow-up, 70% of the patients were alive without disease, with a median cancer-specific survival (CSS) of 133 months. The median CSS was 129 months among luminal tumors, 116 months for triple-positive, 117 months for triple-negative, and 91 months for HER2 super-expressors (p=0.008). The median SCC of the patients that achieved RCB-0 was 116 months, 89 months for those who had RCB-III, and 27 months for those who presented disease progression (p=0.004). CSS was the same for patients who received or not anthracycline and for those who were treated or not with dense dose schedules. Twenty percent of patients with triple-negative tumors received carboplatin, 52% had RCB-0 versus 34% for those who did not receive carboplatin (p=0.002), however, we did not observe any difference in CSS between these groups (p=0.109). Patients with triple-negative tumors were the only ones in which we observed a direct association between achieving RCB-0 and better CSS and progression-free survival (PFS) (p=0.001 for both). Conclusion: The administration of dose-dense anthracycline, of carboplatin and of anti-HER2 double-blockade increased the rate of RCB-0, nevertheless, this did not translate into improved CSS. Achiving complete pathological response in the triple-negative subtype was was associated with improved CSS and PFS.

Citation Format: Monique Celeste Tavares, Marcelle G Cesca, Fernanda A Oliveira, Poliana Andrade, Camilla A Fogassa, Rafaela Pirolli, Bruna R Mattos, Mariana P Xerfan, Sinara Figueiredo, Fernando AB Campos, Vinicius F Calsavara, Solange M Sanches, Fabiana B Makdissi, Cynthia A Bueno, Marina Sonagli, Marina Canal, Vladmir CC Lima. Neoadjuvant therapy outcomes in non metastatic invasive breast carcinomas - Results from a large Brazilian cohort [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-16-30.