Abstract P1-19-07: Real-world characteristics, treatment patterns, and overall survival in patients with metastatic breast cancer (mBC) and CNS metastases

Background: CNS metastases are reported in about 10 to 15%. Knowledge about the management of these patients are limited because they are excluded from clinical trials due to its poor prognosis and morbidity. In these study, we aim to describe characteristics, treatment patterns, and overall survival (OS) of patients of mBC with CNS metastases at Instituto Nacional de Cancerologia de Mexico (INCan) from january 2007 to december 2015. Methods: We include patients with histological diagnosis of mBC and tumoral activity in the CNS (at diagnosis or during de follow-up). mBC subtype was defined using HER2 and hormone receptor (HR) status by immunohistochemistry; systemic treatment, and mortality data were used to characterize mBC with CNS involment. Results: During the study period, we found 1272 patients diagnosed with metastatic disease, of whom 408 had CNS disease (novo/recurrence) the median follow up was 52 months. Table 1 describes the percentage of CNS metastases by subtype, clinical characteristics at diagnosis and median OS. Almost all patients (85.6%) were candidate to holocranial radiotherapy; after that, systemic treatment varied according to the subtype of mBC; 69.1% of TN received CT (26% based on platinum); 75.3% of HER2+ received systemic treatment, all included antiher2 therapy; luminal subtype, no one were treated with endocrine therapy. Conclusions: HER2 positive breast cancer patients have the highest prevalence of CNS metastases, whereas luminal has the lowest. Patients with HER2+ and CNS metastases commonly receive treatment based on anti-HER2 therapy, maybe this target treatment contribute to the better survival achieved than patients with luminal or TN subtype. mBC with CNS metastases continues in the real world to be an unmet medical need. Citation Format: Alvarado-Miranda A, Cabrera-Galeana P, Munoz-Montano WR, Lara-Medina F, Bargallo-Rocha E, Arrieta-Rodriguez O, Perez M, Porras-Reyes F, Mohar-Betancourt A, Gamboa C. Real-world characteristics, treatment patterns, and overall survival in patients with metastatic breast cancer (mBC) and CNS metastases [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 P1-19-07.