The Study: In the meantime, this meta-analysis of 17 international studies of various designs aims to pool data to help answer questions regarding safety and efficacy as we await results of prospective trials. Importantly, all but two of these studies included exclusively patients with melanoma while the remaining two included renal cell carcinoma and NSCLC. Among those with available survival data, patients with brain mets treated with SRS were stratified into three cohorts based on timing of immunotherapy  before SRS (n=49),  after SRS (n=86), or  during SRS (n=83). Side note: “during” was within 4 weeks whenever explicitly defined. Rates of overall survival at one year separated quite nicely to  41%,  56%, and  65%. Among 214 patients with available intracranial control data, rates at one year were  12%,  29% and  38%. Among 919 brain mets with available local control data, rates were 89% with concurrent immunotherapy and 68% with immunotherapy before or after. Only two studies had data about radionecrosis in relation to timing of immunotherapy where there weren’t clear differences, so toxicity effects remains to be elucidated.
Bottom Line: Here’s the largest data yet that immunotherapy concurrent with SRS may improve efficacy, at least in melanoma where it makes a lot of sense given intracranial control rates with immunotherapy alone. | Lehrer, Radiother Oncol 2018