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

PURPOSE: 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.

METHODS: 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.

RESULTS: Median age was 31 years and number of BM was three. Fifteen patients presented with BM at diagnosis, while 48 developed BM at a median time of 8.4 months from diagnosis. At a median follow-up of 3.6 years, 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, 39 Gy, 40-50 Gy, and ≥ 50 Gy 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).

CONCLUSIONS: 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.