Patient Reported Outcomes After Radiation Therapy and Other Treatments for Primary Brain Tumors

Abstract

Purpose/Objective(s): Radiation is hypothesized to potentiate the efficacy of the immune response to tumor cells. Here, we aim to retrospectively characterize the treatment effect of stereotactic radiosurgery (SRS) and whole brain radiation therapy (WBRT) in a cohort of patients with intracranial metastases. Specifically we examined intracranial disease progression following radiation with and without concurrent immunotherapy. Materials/Methods: We identified metastatic non-small cell lung cancer (NSCLC) and metastatic melanoma patients who had intracranial metastases treated with radiation. Radiation treatments consisted of WBRT or SRS at a single institution from 2011-2014. We retrospectively reviewed patient demographics, pathology, oncologic treatment course, and radiographic imaging. Patients were defined as having concurrent immunotherapy if a cycle of Ipilimumab or Nivolumab was given within thirty days pre or post-radiation. Progression free survival (PFS) was defined from date of intracranial radiation to intracranial progression and overall survival (OS) was defined from date of intracranial radiation to date of death. Patients were categorized as having no intracranial progression, local progression within the treatment field, and/or new metastatic disease. The absolute number of new intracranial metastases was recorded following RT. Data was analyzed using Kaplan-Meier survival curves, unpaired two-tailed t-test and Fisher’s exact test. Results: We included 74 adults with metastatic melanoma (nZ51) or NSCLC (nZ23) treated for intracranial metastases with SRS (nZ46) or WBRT (nZ28). In total 23 patients were treated with Ipilimumab or Nivolumab and 17 of these patients were treated concurrently with radiation. PFS and OS for this cohort was a median of 15 months (range:1-51 mo) and 27 months (range:6-76mo). At the time of intracranial progression, 93%of SRS patients who received SRS alone had new intracranial metastases compared to 53% in patients who received concurrent immunotherapy (pZ0.0006, OR 17.14, 95% CI:2.97-99.1). SRS patients who did not receive concurrent immunotherapy had a mean of 7 (range 0-35, SEM 1.49) subsequent brain metastases compared to amean of 1 (range 0-5, SEMZ0.43) in patients who received concurrent immunotherapy (p<0.0001). Conclusion: The use of intracranial stereotactic radiosurgery with concurrent immunotherapy was associated with a decrease in the incidence and burden of new sites of intracranial disease. Although SRS is a local treatment modality, these findings suggest a potential abscopal effect when SRS for brain metastases is used in conjunction with immunotherapy. Author Disclosure: L. Chen: None. J. Douglass: None. A.J. Walker: None. A.E. Marciscano: None. M. Lim: None. L.R. Kleinberg: None. P. Forde: None. T.R. McNutt: None. K.J. Redmond: None.