SURG-03. FUNCTIONAL OUTCOMES OF LASER INTERSTITIAL THERMAL THERAPY (LITT) VERSUS RESECTION IN THE TREATMENT OF LESIONS IN OR NEAR THE PRIMARY MOTOR CORTEX

Abstract INTRODUCTION Laser interstitial thermal therapy (LITT) is a minimally-invasive treatment option for radiographically-progressive (RP) brain metastases. This study compares the functional outcomes of LITT vs resection (RS) for lesions in or near the primary motor cortex (PMC). METHODS Retrospective review was performed of patients treated for PMC lesions by LITT or RS. Functional outcomes were graded relative to pre-treatment symptoms and categorized as improved, stable, or worsened at 30, 90, and 180 days post-LITT/RS. RESULTS 36 patients were identified with median follow-up of 194 days (IQR 72-503), age 64 years (57-72), and estimated baseline KPS 80 (80-90). 35 (98%) had pre-treatment weakness or motor seizure; 15 (42%) received LITT and 21 (58%) RS; all RS were performed with intra-operative motor mapping while LITT were not. All LITT patients were treated for RP lesions (radiation necrosis (RN) or disease progression) vs. 24% of RS patients (p< 0.01). LITT patients trended towards smaller lesions (1.9 cm vs 2.7 cm, p=0.03) and were more likely to show RN (67% vs 5%, p< 0.01) and be discharged home (87% vs 52%, p=0.04), with shorter ICU (0 vs 1 day, p< 0.01) and hospital stays (1 vs. 2 days, p< 0.01). At 30 days, 89% of surviving patients who received RS had stable or improved symptoms, compared to 46% of the LITT cohort (p=0.02). At 90 days, the difference was 88% to 50% (p=0.07), and at 180 days 100% to 80% (p=0.2941). CONCLUSIONS In the short term (30 days), patients with PMC lesions have better functional outcomes when treated with RS compared to LITT, while those who survive to the 180-day timepoint experience similar outcomes. These differences are likely due to transient, expected post-LITT edema that subsides with time. Taken together, prognosis and patient priorities are important considerations in the decision between LITT and RS.