Abstract P4-07-40: Magnetic resonance imaging (MRI) and clinicopathological analysis of triple-negative breast cancer (TNBC) patients (pts) treated with primary anthracyclines(A)/taxanes(TX)-based chemotherapy

Abstract

Abstract Background Radiological complete response (CR-MRI) to neoadjuvant chemotherapy (NAC) by MRI predicts pathologic complete response (pCR) rates in pts with TNBC treated preoperatively with A/TX-based regimens and in some studies, it correlates with disease-free survival (DFS). The main aim of this study was to assess the relevance of the MRI response to primary chemotherapy associated with clinical stage and HER2 expression (Zero vs Low), in a cohort of 143 TNBC pts treated with A and TX +/- carboplatin (CP) in the NAC setting. Methods Retrospective study of pts treated with NAC for TNBC between January 2002 and June 2021, who underwent MRI to assess tumour response before NAC, after 4 cycles of anthracycline and cyclophosphamide (AC) and after TX. Survival analysis was based on the Kaplan-Meier and survival curves were compared using the log-rank test. A p value of less than 0.05 was considered as statistically significant. Results A total of 143 TNBC pts with a median age of 52 years; 7, 63 and 73 pts had stage I, II and III disease, respectively. The NAC regimen consisted in 117 pts 4 cycles of AC followed by TX and in 24 pts the same adding CP (in 21 pts with non-CR-MRI, 2 with CR-MRI and 1 without MRI after AC). PCR was observed in 41%. Of 30 pts with CR-MRI after AC, 83% obtain a pCR (p< 0.001), and of 52 pts with CR-MRI at the end of NAC, 70.7% obtain a pCR (p< 0,001) of which 90% had a CR-MRI after AC. Adding CP increased pCR by 6% (p=0.564). According HER2-zero vs low expression, the pCR was 38% and 47% respectively, with no significant differences. With a median follow-up of 60 months, 34% recurred and 16% died of TNBC. In pts with pCR, the DFS at 5 years (y) was 96% and 47% for pts without pCR (p< 0.001), with a DFS of 91% if CR-MRI at the end of NAC and 48% if non-CR-MRI (p< 0.001). In HER2-Zero tumours the DFS at 5 y was 64% vs 66% in HER-2 low. Interestingly, overall survival (OS) at 5 y was 72% in HER2-Zero and 84% in HER2-low (p=0.080). Conclusions Performing serial MRI in the course of NAC in TNBC may be a reliable indicator of pCR, adding platinum to TX in pts with CR-MRI may increase pCR rate. HER2-Zero expression in TNBC, seems to confer worse OS rates. Citation Format: Marina Sierra Boada, Luis Antonio Fernandez, Elsa Dalmau, Gemma Llort, Maria Marin, Pablo Andreu, Natalia Lopez, Carla Climent, Marta Rodriguez, Sandra Soriano, Miquel Angel Segui. Magnetic resonance imaging (MRI) and clinicopathological analysis of triple-negative breast cancer (TNBC) patients (pts) treated with primary anthracyclines(A)/taxanes(TX)-based chemotherapy. [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-07-40.