Abstract P3-05-49: Number of involved organs at baseline is prognostic for overall survival in patients with metastatic breast cancer: Results from the AGMT_MBC-Registry

Abstract

Abstract Background: Hormone-receptor (HR) status, HER2 Status, de novo metastatic disease, distant recurrence-free interval (DRFI), and visceral disease are known prognostic factors in metastatic breast cancer (MBC). Therefore, in the majority of clinical trials, randomization is stratified for these parameters. Whether the number of involved organs at baseline has an additional prognostic value was examined in this analysis. Patients and methods: The AGMT-MBC-Registry is a multicenter nationwide ongoing retrospective and prospective registry for MBC patients in Austria. In this analysis, patients with known HR status, HER2 status, and available survival data were included. Multivariable hazard ratios were estimated by COX proportional hazard models. For variable selection a backward stepwise model selection using the Akaike information criterion was performed. Results: As of 04/05/2022, 2,235 patients have been included in the registry, of which 1,840 patients fulfilled the inclusion criteria. In two different multivariable COX proportional hazard models for overall survival, the number of involved organs was a highly statistically significant independent prognostic factor: (1) a model including the number of involved organs at baseline together with known prognostic factors (see Table 1); (2) a stepwise selection model additionally including menopausal status and involved metastatic organ sites (bone, liver, lung, brain, and lymph nodes) separately. This effect was maintained in sensitivity analysis taking different breast cancer subtypes as well as visceral and non-visceral disease into account. Conclusion: The number of involved organs at baseline is an independent prognostic factor in MBC and should be considered as a stratification factor in randomized trials. Table 1. Multivariable Model for overall survival. Citation Format: Gabriel Rinnerthaler, Simon P. Gampenrieder, Christoph Tinchon, Andreas Petzer, Marija Balic, Sonja Heibl, Margit Sandholzer, August F. Zabernigg, Daniel Egle, Christopher Hager, Petra Pichler, Florian Roitner, Johannes Andel, Kathrin Strasser-Weippl, Michael Knauer, Michael Hubalek, Christian F. Singer, Richard Greil. Number of involved organs at baseline is prognostic for overall survival in patients with metastatic breast cancer: Results from the AGMT_MBC-Registry [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 P3-05-49.