Melanoma brain metastases: is it time to eliminate radiotherapy?

Abstract

Immunotherapy has demonstrated efficacy in treatment of intracranial metastasis from melanoma, calling into question the role of intracranial radiotherapy (RT). Herein, we assessed the utilization patterns of intracranial RT in patients with melanoma brain metastasis and compared outcomes in patients treated with immunotherapy alone versus immunotherapy in addition to intracranial RT. We queried the National Cancer Database (NCDB) for patients with melanoma brain metastases treated with immunotherapy and intracranial RT or immunotherapy alone. Multivariable logistic regression identified variables associated with increased likelihood of receiving immunotherapy alone. Multivariable Cox regression was used to identify co-variates predictive of overall survival (OS). Propensity matching was used to account for indication bias. We identified 528 and 142 patients that were treated with combination therapy and immunotherapy alone, respectively. Patients with lower comorbidity score were more likely to receive immunotherapy alone. Extracranial disease and treatment at a non-academic center were associated with worse OS. Median OS for all patients was 11.0months. Treatment with stereotactic radiosurgery (SRS) in addition to immunotherapy was superior to immunotherapy alone, median OS of 19.0 versus 11.5months (p = 0.006). Whole brain radiation therapy (WBRT) in combination with immunotherapy performed worse than immunotherapy alone, median OS of 7.7 versus 11.5months (p = 0.0255). For melanoma patients requiring WBRT, immunotherapy alone may be reasonable in asymptomatic patients. For those eligible for SRS, combination therapy may provide better outcomes. Results of ongoing prospective studies will help provide guidance regarding the use of radioimmunotherapy in this population.