Abstract P1-17-05: Prognostic impact of initial treatment modality for brain metastasis in metastatic breast cancer

Abstract

Abstract Background: The routine screening of brain metastasis (BM) is not recommended in patients with metastatic breast cancer (MBC) by guidelines. Due to survival improvement and increased use of magnetic resonance imaging (MRI) contribute the increasing of MBC BM incidence. The incidence of BM and survival from BM were various by molecular subtypes. The prognostic role of early detection of oligo BM and subsequent local treatment by subtypes is not clear. We aimed to compare BM free survival (BMFS) and BM overall survival (BMOS) by both treatment modalities and subtypes. Methods: In the Yonsei Breast Cancer MBC Database, we identified 1252 MBC patients who were diagnosed from 2006 to 2016. Data of 358 MBC patients (127 HR+/HER2-, 80 HR+/HER2+, 64 HR-/HER2+, 87 HR-/HER2-) with BM were available for the analysis. BMFS was defined as the time from the diagnosis of MBC to the diagnosis of BM. MBC patients with initial BM were excluded from analysis of BMFS. BMOS was defined as the time from the diagnosis of BM to any cause of death. Treatment modalities were analyzed as three categories; whole brain radiotherapy (WBRT), stereotactic radiosurgery (SRS), and neurosurgery. Results: Among the 1252 MBC patients, 47.7%, 14.7%, 13.1%, 17.6%, and 6.9% had HR+/HER2-, HR+/HER2+, HR-/HER2+, HR-/HER2-, and unknown subtypes, respectively. The incidence of initial BM were highest among patients with HR-/HER2- (14.5%) and were lowest with HR+/HER2- (5.2%) Incidence of initial metastasisInitial metastatic sitesHR+/HER2-, n(%)HR+/HER2+, n(%)HR-/HER2+, n(%)HR-/HER2-, n(%)Unknown, n(%)PBrain31 (5.2)16 (8.7)12 (7.3)32 (14.5)6 (6.9)<0.001Lung197 (33)72 (39.1)62 (37.8)99 (45)33 (37.9)0.036Liver137 (22.9)46 (25)52 (31.7)56 (25.5)16 (18.4)0.122Bone403 (67.5)109 (59.2)66 (40.2)90 (40.9)48 (55.2)<0.001Distant LN176 (29.5)74 (40.2)60 (36.6)93 (42.3)22 (25.3)0.011Pleura116 (19.4)19 (10.3)23 (14)40 (18.2)13 (14.9)0.045 . The median BMFS was 17.3 months (95% confidence interval (CI); 14.32-20.28) among the all patients with BM. The median BMFS was significantly shorter in the ER-/HER- subtypes (12 months, 95% CI; 20.73-31.67), and followed by ER-/HER2+ (14.8 months, 95% CI; 11.50-18.10), ER+/HER2+ (20.9 months, 95% CI; 16.88-24.92), and ER+/HER2- (26.2 months, 95% CI; 20.73-31.67). The median BMOS was significantly better in the SRS (16.8 months; 95% CI; 13.53-20.07) and surgery group (13.4 months, 95% CI; 7.19-19.61) compared with WBRT (6.9 months, 95% CI; 5.04-8.76) and no treatment (1.2 months, 95% CI; 0.32-2.08). Conclusions: Incidence of initial BM and BMFS were significantly different by subtypes. Patients who were treated with SRS or neurosurgery showed better survival compared to WBRT. This findings support to consideration of screening of BM in HER2+ or triple negative subtypes for the early detection of oligo BM. Citation Format: Kim GM, Cho YU, Kim SI, Park S, Park HS, Kim JY, Chun YJ, Sohn J. Prognostic impact of initial treatment modality for brain metastasis in metastatic breast cancer [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 P1-17-05.