Whole Brain Radiation Therapy Improves Overall and Intracranial Progression-Free Survivals in Breast Cancer Patients With Brain Metastases in the Setting of Systemic Treatments

Abstract

To evaluate overall (OS) and intracranial progression-free survival (PFS) effects of whole-brain radiotherapy (WBRT) in breast cancer (BC) patients with brain metastases (BM) in setting of systemic treatments. A retrospective analysis of 105 consecutive female patients admitted for BM from BC between 2013 and 2015 at a single institution was conducted. Patient and treatment characteristics were collected and survival data till December 1 2016 were calculated. Local radiotherapy (RT) modalities were classified: none, <30, 30-39 and ≥40 Gy of WBRT; none, <50 and ≥60 Gy of largest BM tumor site dose; gamma-knife/SRS use or not. Cox proportional hazard regression models were used to estimate the independent effects of WBRT regimen on OS and PFS. Beside RT modalities, final model variables included age at BM, ECOG, number of brain lesion (1, 2, 3,≥4), Ki67 level, BM chemotherapy, endocrine therapy, target drug use, BM tumor resection status, and meningeal involvement after the extensive screening univariate analyses on others. p<0.05 as ns. BM mean age (range) was 53 (27-82) years old. By the WBRT regiment order above, number (median days of OS vs. PFS) of patients was 51(271 vs. 156 days), 11(271 vs. 144), 13(571 vs. 515) and 30(402 vs. 399) with K-M log-rank test p= 0.11 vs. p=0.04. Compared with none, other WBRT regimen's univariate hazard ratios (HRs) of OS were 1.456 (ns), 0.621 (ns) and 0.658(ns) and their HRs of PFS were 1.321 (ns), 0.581 (ns) and 0.556(p=0.03). On multivariate analyses, their HRs of OS were 1.078 (ns), 0.335(p=0.02), 0.335 (p=0.01) and their HRs of PFS were 0.928 (ns), 0.276 (p=0.003) and 0.288 (p=0.001). WBRT associates independently with improved OS and PFS in setting of modern local and systemic treatments for BM patients from BC. WBRT ≥30 Gy is adequate for both extended survivals.