Radical Laser Interstitial Thermal Therapy Ablation Volumes Increase Progression-Free Survival in Biopsy-Proven Radiation Necrosis.

Abstract

Treatment for surgically inaccessible medically refractory cerebral radiation necrosis (RN) has remained limited. Recently, laser interstitial thermal therapy (LITT) has gained traction as an effective means of treating these lesions but limited data are available regarding the effect of ablation size on patient outcome. Therefore, this study analyzed various outcome measures as a function of ablation volume/diameter for a series of 20 patients with surgically inaccessible biopsy-proven RN. Twenty patients with biopsy-proven RN treated with LITT from 2013 to 2018 at our institution were retrospectively reviewed. Local progression-free survival (PFS), overall survival, and steroid dependence were analyzed with Kaplan-Meier and Cox regression analysis for ablation volume/diameter. Comparison of preoperative and postoperative Karnofsky Performance Status was conducted with a matched paired t test. Patients with subtotal ablation (<100% increase in pre-LITT lesion volume or <0 mm increase in pre-LITT lesion diameter) had higher risk of local disease progression (hazard ratio, 12.4; P = 0.004) compared with patients with total ablations. Patients who received radical ablations (>200% increase in pre-LITT lesion volume or >2 mm increase in pre-LITT lesion diameter) showed the most favorable PFS (P < 0.0458 and P < 0.0378, respectively). There was no difference in post-LITT Karnofsky Performance Status and time to steroid freedom between ablation groups. Overall survival increased with radical diametric ablation (P = 0.0401). Although LITT has proved to be an effective salvage therapy for patients with RN, detailed volumetric studies have not been explored. Our results suggest that radical ablations have the potential to increase PFS.