Stereotactic Radiosurgery of Brain Metastasis in Patients with a Poor Prognosis: Effective or Overtreatment?

Stereotactic radiosurgery (SRS) of brain metastasis in patients with a poor prognosis remains controversial. Here, we compared results of SRS alone to whole brain radiotherapy (WBRT) in poor-prognosis patients and defined the most important unfavorable prognostic factors related to early death after SRS alone.

In this retrospective analysis of prospective SRS data, 180 patients with brain metastases not previously treated with WBRT were analyzed. Results of SRS were compared to WBRT by propensity score matching in patients with a poor prognosis defined by graded prognostic assessment (GPA) <2. Further, SRS patients were divided into training (n=82) and validation (n=48) cohorts. Overall survival (OS) and the risk of early death were defined by univariable and multivariable analyses.

Median survival of the WBRT and SRS cohorts was 86 days (IQR: 38-172 days) and 201 days (IQR: 86-not reached), respectively (p<0.0001). OS in patients with GPA<2 was significantly longer in the SRS vs WBRT group (123 vs 58 days; p=0.008). Survival was longer in the SRS group in a propensity score matched analysis. In multivariable analysis, GPA (OR: 0.44, 95%CI: 0.21-0.95; p=0.001), extensive extracranial disease (OR: 0.13, 95%CI: 0.02-0.66; p=0.013), and serious neurological deficits (OR: 0.13, 95%CI: 0.04-0.45; p=0.001) were associated with early death. If one factor was favorable, 73% (training) and 92% (validation) of patients survived three months. Patients with GPA <2 presenting with serious neurological deficits and extensive extracranial disease had a low expected benefit due to the highest risk of death within three months (AUC: 0.822 training; 0.932 validation).

SRS is a viable treatment option for patients with a poor prognosis defined as GPA <2. Good neurological status, extracranial oligometastatic disease, or GPA ≥2 should be present to justify SRS in patients with brain metastases.