Abstract P1-15-16: Pathological complete response rates with the addition of carboplatin to standard neoadjuvant chemotherapy in a cohort of real–world patients with triple negative breast cancer

Abstract

Abstract Objectives: Addition of carboplatin to standard neoadjuvant chemotherapy (NACT) for triple negative breast cancer (TNBC) remains controversial. There are several randomized trials showing that carboplatin increases the likelihood of achieving pathological complete response (pCR) in TNBC. Patients with TNBC who achieve pCR has been shown to have better disease-free and overall survival. The aim of this study was to asses the impact of adding carboplatin to standard NACT in TNBC in terms of pCR rates and toxicity. Methods:In this cross-sectional study, 252 consecutive patients with primary TNBC who were submitted to neoadjuvant chemotherapy between 2013 and 2018, in a single center, were selected. Patients with biopsy-confirmed TNBC, previously untreated, with clinical stages I-III were included (n=179). Clinical pathological features, pathological response, treatment protocol, and toxicities were analyzed and considered for statistical analysis. Eighty patients treated from 2013 to 2015 received doxorubicin plus cyclophosphamide once every 3 weeks (AC) for four cycles, followed by 12 weeks (wP) or every 3 weeks (P) paclitaxel(AC-T group). Ninety-nine patients, treated from 2015 to 2018 had four cycles of AC followed by wP plus weekly carboplatin (Cb) area under curve (AUC) 1.5-2.0 (AC-TCb group). Pathologic response was determined locally, and pCR was defined as the absence of residual invasive disease with or without ductal carcinoma in situ in the breast and axilla. Results: Data from 179 patients were included in the analysis (AC-T: n=80; AC-TCb: n=99). Patients in AC-TCb group had a median age of 51.7 years vs. 47.4 years in AC-T group, p=0.01. In AC-TCb group 61.6% of patients were postmenopausal vs 43.7% in AC-T group, p=0.03. The distribution of clinical stage in groups AC-TCb and AC-T were as follows: stage I 6.0% vs 0%; stage II 42.4% vs 43.7%; stage III 51.6% vs 56.3%, respectively (p=0.02). In AC-TCbgroup, 34 patients (35.0%) had pCR in comparison to 20 patients (25.0%) on AC-T group (p=0.22). Pathological stage distribution in groups AC-TCb and AC-T were: stage I 24.7% vs 33.7%; stage II 23.7% vs 26.3%; stage III 16.4% vs 15%, respectively (p=0.42). More than 85.0% of patients in AC-TCb group received at least 9 weeks of carboplatin and less than 20.0% required dose reduction due to toxicity.Conclusions: An improved pathological complete response for TNBC patients submitted to standard NACT plus carboplatin was observed. The results are in accordance with previous studies demonstrating that the addition of carboplatin to NACT improves pCR rate in TNBC with a favorable risk to benefit profile. Therefore carboplatin might be a potential component of NACT and should be considered in this context. Distribution of patients with TNBC submitted to NACT with AC-T and AC-TCb according clinical–pathological characteristicsClinical pathological characteristicsAC-T n= 80AC-TCb n=99pMenopausal 0.03yes3561 no4538 Clinical stage 0.02I06 II3542 III4551 Histologic type 0.25IDC8096 others03 Histologic grade 0.86101 22932 35164 Pathological stage 0.42O2034 I2724 II2123 III1216 pCR 0.22yes2034 no6063 Citation Format: Ramalho S, Natal RdA, Cardoso Filho C, Xavier MB, da Silva AER, Silva LR, Vasconcelos V, Reinert T, Coelho GP, Silva GRdP, dos Santos CC. Pathological complete response rates with the addition of carboplatin to standard neoadjuvant chemotherapy in a cohort of real–world patients with triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-15-16.