SURG-02. LASER INTERSTITIAL THERMAL THERAPY FOR BRAIN METASTASES: OUTCOMES AND PREDICTORS OF LOCAL RECURRENCE

BACKGROUND: LITT has been used to treat recurrent brain metastasis after stereotactic radiosurgery (SRS). Little is known about how best to assess the efficacy of treatment, specifically the ability of LITT to control local tumor progression post-SRS. Objectives: Evaluate the predictive factors associated with local recurrence after LITT. METHODS: Retrospective study with consecutive patients with brain metastases treated with LITT. Based on radiological aspects, lesions were divided into progressive disease after SRS (recurrence or radiation necrosis) and new lesions. Primary endpoint was time to local recurrence. RESULTS: 61 consecutive patients with 82 lesions (5 newly diagnosed, 46 recurrence and 31 radiation necrosis). Freedom from local recurrence at 6 months was 69.6%, 59.4% at 12, and 54.7% at 18 and 24 months. Incompletely ablated lesions had a shorter median time for local recurrence (p< 0.001). Larger lesions (>6cc) had shorter time for local recurrence (p=0.03). Dural based lesions showed a shorter time to local recurrence (p=0.01). Tumor recurrence/newly diagnosed had shorter time to local recurrence when compared to RN lesions (p=0.01). Patients receiving systemic therapy after LITT had longer time to local recurrence (p=0.01). In multivariate Cox-regression model the HR for incomplete ablated lesions was 4.88 (p< 0.001), 3.12 (p=0.03) for recurrent tumors, and 2.56 (p=0.02) for patients not receiving systemic therapy after LITT. Complication rate was 26.2%. CONCLUSIONS: Incompletely ablated and recurrent tumoral lesions were associated with higher risk of treatment failure and were the major predicting factors for local recurrence. Systemic therapy after LITT was a protective factor regarding local recurrence.