Abstract P1-17-06: Outcomes of central nervous system radiotherapy for metastatic breast cancer: The Royal Marsden experience 2000 - 2016
Authors: Kothari G , De Ieso PB , Mohammed K , Ross GM 
Published: February 2018

Abstract
Background: Breast cancer (BC) is one of the most common malignancies affecting women. Brain metastatses (BM) are frequently seen in BC, and can have devastating consequences with significant associated morbidity and mortality. Whole brain radiotherapy (WBRT) is commonly used to treat BM, with variable use of stereotactic radiotherapy (SRT). This study reports on the outcomes of BC patients with BM who received central nervous system (CNS) radiotherapy over a 17-year period at the Royal Marsden Hospital (RMH).
Methods: We included all BC patients who had WBRT with or without SRT for intra-parenchymal BM secondary to BC at RMH between 2000 and 2016 inclusive. Instances of meningeal involvement were excluded from analysis. Data collected included age, histological subtype, tumor grade, stage at original BC presentation, receptor status, date of BM diagnosis, number of metastases, size of largest BM, Eastern Cooperative Oncology Group (ECOG) score, presence of extra-cranial metastases (ECM), neurosurgery (NS) and stereotactic radiotherapy (SRT) details, and date of last follow up or death. Univariate and multivariate analyses were performed to analyze the effect of each variable on overall survival (OS) from date of BM.
Results: A total of 426 patients were included with a median age of 54 years at BM diagnosis and a median time to BM from BC diagnosis of 43 months. At diagnosis, 94% had invasive ductal carcinoma (IDC) and 70% had Grade 3 disease. Stage IV disease at original BC presentation was seen in 18% of patients. Estrogen receptor (ER+) was positive in 57% (n = 236), progesterone receptor (PR+) in 44% (n = 147), and HER2 (HER2+) in 44% (n = 166). Twenty-two percent (n = 89) were triple negative (TN). Median number of BM was 4 (range 1 – 205) and 20% (n = 72) of patients had only 1 BM. Average size of the largest lesion was 26 mm (range 1 – 75). The ECOG score was 0 – 1 in 61% of patients. Ten percent of patients (n = 44) underwent SRT and 10% (n = 43) underwent NS. Three hundred and eighty patients had died at the time of analysis. Median OS from date of BM was 6.4 months. On univariate analysis, age &lt; 60 years at BC diagnosis (8.1 vs. 4.0 months, p = 0.0007) and BM diagnosis (8.0 vs. 5.6 months, p = 0.03), ECOG status 0-1 (9.6 vs. 4.0 months, p = &lt;0.0001), ER+ (8.0 vs. 6.0 months, p = 0.0007), PR+ (7.6 vs. 6.9 months, p = 0.04), HER2+ (10.5 vs. 5.6 months, p &lt; 0 .0001), SRT (20.3 vs. 5.9 months, p &lt; 0.0001) and NS (20.3 vs. 6.2 months, p &lt; 0.0001) significantly predicted for improved OS. Triple negative status predicted for worse survival (5.6 months vs. 8.1 months, p &lt; 0.0001). On multivariate analysis, ECOG status, ER+, HER2+, treatment with SRT and NS were independent predictors for OS.
Conclusions: This study confirms substantial heterogeneity of prognosis in patients with BM from BC, with significantly improved survival in patients selected for SRT or surgery. Further studies are required to optimize the role of CNS radiotherapy techniques such as SRT and hippocampal sparing WBRT in patients with a favorable prognosis.
Citation Format: Kothari G, De Ieso PB, Mohammed K, Ross GM. Outcomes of central nervous system radiotherapy for metastatic breast cancer: The Royal Marsden experience 2000 - 2016 [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-17-06.