Authors: Javier Figueroa, MD, PhD; Alexa Semonche, BS; Stephanie Magoon; Ashish Shah, MD; Ricardo Komotar, MD; Michael Ivan, MD (Miami, FL)

Introduction: Laser-induced thermotherapy (LITT) offers a minimally-invasive treatment option for glioblastomas (GBM) which are relatively small or in eloquent areas. While laser ablation for malignant gliomas is known to be safe and effective, the role of the subsequent immune response in not well established. In this study we analyze the prognostic potential of edema volume and acute inflammation, quantified as neutrophil-to-lymphocyte ratio (NLR), in predicting response to treatment and length of survival. Methods: Twenty-one patients were identified with new or recurrent glioblastomas that were determined to be candidates for LITT. Laser ablation was performed using standard solid tumor protocol for treatment volume, intensity and duration. Edema volume was quantified using follow-up MRI imaging, while retrospective chart review was performed to calculate NLR and survival. Results: In patients treated with LITT for GBM, peritumoral edema volumes did not significantly change post-operatively (p > 0.200), while NLR significantly increased (p = 0.0002). The degree of NLR increase correlated with longer overall survivals, and ROC analysis demonstrated an area under the curve of 0.827 (p = 0.112). A delta-NLR cutoff of 7.0 results in positive and negative predictive values of 78% and 75%, respectively, in predicting overall survival > 1 year. Patients with with delta-NLR > 7.0 lived significantly longer that those with delta-NLR < 7.0, median survival 440 days compared to 239 days (p = 0.0297). Conclusion: Here we show that monitoring the inflammatory response after LITT therapy in GBM patients offers a prognostic tool to determine treatment efficacy and overall survival.