Abstract P1-12-02: Prognostic factors and survival according to tumor subtype in women presenting with breast cancer brain metastases at initial diagnosis

Abstract

Abstract Background: Breast cancer represents one of the most common causes of brain metastases. The occurrence of this event is a catastrophic complication of metastatic breast cancer, associated with poor prognosis. However, the presence of brain metastases at the time of initial breast cancer diagnosis (BMIBCD) is uncommon. Because of this, the prognostic assessment and management of patients (pts) who present with BMIBCD is very challenging. The aim of this study was to analyze the influence of tumor subtype compared with other prognostic factors in the survival of pts who present with BMIBCD. Methods: We evaluated women with brain metastases at the time of initial diagnosis of microscopically confirmed breast cancer, reported to the Surveillance, Epidemiology and End Results (SEER) 18 registries program from 2010 to 2013. Pts with other primary malignancy either before or after breast cancer were excluded. Pt characteristics were compared between tumor subtypes. Univariate and multivariate analyses were performed to determine the effects of each variable on overall survival (OS). Results: Seven hundred forty pts were included. Median age was 60 years (range 26-93). After a median follow-up of 6 months (range 1-48), median OS for the whole population was 10 months and 20.7% of pts were alive at 36 months. At diagnosis, brain was the only site of metastasis in 125 pts, whereas 66.2% of pts had metastases in bone, 33.2% in liver and 44.7% in lung. Tumor subtype distribution was: 46.6% hormone receptor (HR)+/HER2-, 17% HR+/HER2+, 14.1% HR-/HER2+ and 22.3% triple negative (TN). Pts with TN brain metastases had higher grade (p<0.0001), higher rate of brain only (p=0.001) and lung metastases (p=0.03), had lower rates of bone metastases (p<0.0001) and were more likely to die from breast cancer (p<0.0001). Univariate analysis showed that older age (p=0.0002), black race (p=0.004), lobular histology (p=0.01), unmarried pts (p=0.01), the presence of liver (p<0.0001) and lung metastases (p=0.002) and TN pts (median OS 6 months; p<0.0001) had worse prognosis. The HR+/HER2+ subtype had the longest OS with a median of 22 months. In multivariate analysis, older age (hazard ratio 1.8; p=0.001), lobular histology (hazard ratio 2.08; p=0.006), TN subtype (hazard ratio 2.25; p<0.001), liver metastases (hazard ratio 1.6; p=0.001) and unmarried pts (hazard ratio 1.39; p=0.04) had significantly shorter OS. Race, tumor grade, bone metastases, lung metastases and brain only metastases had no association with OS. Conclusions: To our knowledge, this is the largest study of BMIBCD. Although the prognosis of these pts is generally poor, it is important to notice that 20.7% of pts were still alive 3 years after diagnosis. There were substantial differences in OS according to tumor subtype, TN pts had the shortest OS. HR+/HER2- represented the largest proportion of cases, therefore these pts should not be ignored when designing clinical trials for pts with brain metastases. In addition to tumor subtype, other independent predictors of OS are age at diagnosis, marital status, histology and liver metastases. Citation Format: Leone JP, Leone J, Zwenger AO, Iturbe J, Leone BA, Vallejo CT. Prognostic factors and survival according to tumor subtype in women presenting with breast cancer brain metastases at initial diagnosis [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-12-02.