Abstract P5-06-29: Prognosis of triple negative metastatic breast cancer (MBC): Results from the AGMT_MBC-Registry
Authors: Rinnerthaler Gabriel , Gampenrieder Simon P , Petzer Andreas , Tinchon Christoph , Fuchs David , Balic Marija , Heibl Sonja , Rumpold Holger , Egle Daniel , Zabernigg August F , Singer Christian F , Andel Johannes , Hubalek Michael , Knauer Michael , Greil Richard 
Published: March 2020

Background: Triple-negative breast cancer (TNBC) comprises a heterogeneous group of diseases which are generally associated with poor prognosis. In recent years, major progress has been made in the treatment of metastatic breast cancer (MBC), especially for hormone receptor (HR) positive and HER2 positive MBC. In contrast, for most TNBC patients no targeted treatment options are available. Population-based data on overall survival (OS) of triple negative MBC are scarce and were totally missing for the Austrian population. Here, we present the overall survival (OS) results of triple-negative breast cancer patients included the MBC registry of the Austrian Study Group for Medical Tumor Therapy (AGMT). Patients and methods: The AGMT_MBC-Registry is a multicenter nationwide ongoing retrospective and prospective registry for MBC patients in Austria. Unadjusted, univariate survival probabilities of OS were calculated by the Kaplan-Meier method and multivariate hazard ratios (HR) were estimated by Cox regression models. In this analysis only patients with triple-negative MBC with available survival data were included. Results: As of 31/01/2019, 1,253 patients were included in the AGMT-MBC-Registry. Out of 1,219 evaluable patients with available survival data, 192 (17.8%) were triple-negative. Mean age at diagnosis of MBC was 59 (range 27-89), 44 patients (22.9%) were diagnosed with de novometastatic disease, 89 patients (46.4%) with metachronous MBC had a disease free survival (DFS) &lt; 24 months, 134 (69.8%) were treated with (neo)adjuvant therapy, 114 (59.4%) had visceral disease at diagnosis of MBC, and number of involved metastatic sites at diagnosis was 1 in 102 (53.1%), 2 in 49 (25.5%), 3 in 24 (12.5%) and &gt; 3 sites in 17 (8.9%) patients. Fifty-nine patients (49.5%) received at least one treatment-line which included bevacizumab. Bevacizuamb was combined with capecitabine, paclitaxel and gemcitabine in 38, 68 and 5 patients, respectively. Median OS of TNBC was 15.2 months (95% CI 11.4-18.9), compared to 32.9 months (95% CI 29.7-35.7) in the overall cohort. In multivariate analysis including established risk factors and clinically relevant variables, only three variables were significantly associated with OS in TNBC patients: disease free survival (&lt;24 months vs ≥ 24 months or de novo MBC: HR 1.80 [95% CI 1.29-2.51]), visceral disease (yes vs no: HR 1.75 [95% CI 1.22-2.52]), and number of metastatic sites at initial diagnosis (2-3 vs 1: HR 1.81 [95% CI 1.26-2.60], &gt; 3 vs 1: HR 3.05 [95% CI 1.66-5.61]). Conclusion: The poor prognosis of TNBC was confirmed in this population-based analysis. Besides known prognostic factors like de novo metastatic disease, DFS and visceral disease, the number of metastatic sites at initial diagnosis was identified as a novel independent prognostic factor in TNBC.

Citation Format: Gabriel Rinnerthaler, Simon P Gampenrieder, Andreas Petzer, Christoph Tinchon, David Fuchs, Marija Balic, Sonja Heibl, Holger Rumpold, Daniel Egle, August F Zabernigg, Christian F Singer, Johannes Andel, Michael Hubalek, Michael Knauer, Richard Greil. Prognosis of triple negative metastatic breast cancer (MBC): Results from the AGMT_MBC-Registry [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 P5-06-29.