High-dose radiation therapy is needed for intracranial control and long-term survival in patients with non-seminomatous germ cell tumor brain metastases

Abstract

The presence of brain metastases (BM) in patients with non-seminomatous germ cell tumor (NSGCT) is associated with poor prognosis. While radiation therapy (RT) is an important treatment for patients with NSGCT BM, there is a paucity of data on the optimal regimen. We sought to investigate the impact of RT on clinical outcomes in patients with NSGCT BM. Patients with NSGCT BM who received RT at our institution from 2002 to 2017 were included. Sixty-three consecutive patients were identified. Clinical factors associated with intracranial control (ICC) and overall survival (OS) were evaluated using cox regression analysis and Kaplan Meier method. Median age was 31years and number of BM was three. Fifteen patients presented with BM at diagnosis, while 48 developed BM at a median time of 8.4months from diagnosis. At a median follow-up of 3.6years, ICC and OS were 39.7% and 30.1%. On multivariate analysis, ICC (hazard ratio [HR] = 0.93, p = 0.03) and OS (HR = 0.93, p = 0.005) were both significantly associated with biologically effective dose (BED) of RT. The 4-year OS of patients who received BED < 39Gy, 39Gy, 40-50Gy, and ≥ 50Gy were 0%, 14.7%, 34.1%, and 70.0%, respectively. Patients who achieved ICC after RT were able to achieve long-term survival (4-year OS 68.1% vs. 0%, p < 0.0001). Our data supports that a higher BED is required for durable ICC, and that ICC is needed for patients with NSGCT to achieve long-term survival. Prospective studies evaluating radiation dose-escalation for the treatment of NSGCT BM should be considered.