LOCL-14 FACTORS ASSOCIATED WITH TRACT SEEDING AFTER LASER INTERSTITIAL THERMAL THERAPY FOR INTRACRANIAL TUMORS

Abstract

Abstract Laser interstitial thermal therapy (LITT) is a growing minimally-invasive approach for treatment of intracranial tumors. Stereotactic placement of the laser catheter within the target lesion carries a theoretical risk of tract seeding, which could lead to disease progression. A retrospective analysis of patients treated with LITT for biopsy-confirmed tumor from 2016-2020 was conducted to characterize the risk of post-LITT tract seeding. Forty-two patients met inclusion criteria, of whom 23 (54.7%) had primary brain tumors and 19 (45.3%) metastases. Thirty-three (78.6%) lesions were recurrent disease at the time of LITT. On follow-up MRI, 3 patients (7.1%) were identified to have had tumor seeding along the LITT tract resulting in progressing disease. There were no significant differences in tumor histology, pre-operative maximum lesion diameter, number of LITT trajectories, rounds of lasing, or post-LITT radiotherapy or surgery between patients with and without tract seeding. All patients with tract seeding were treated for periventricular lesions (<1cm). Patients with tract seeding were also more likely to have received LITT ablations administered from the superficial to deepest elements of the lesion (p=0.05). The median time to progression post-LITT for patients with tract seeding was significantly shorter than those without (1.1 vs 5.9 months, p=0.02). Additional analyses revealed trends towards longer median tract length (4.0 vs. 2.2 cm, p=0.23) and shorter overall survival (5.4 vs. 14.2 months, p=0.17) in the tract seeding cohort. In summary, tract seeding is an infrequent complication associated with both LITT and traditional biopsy. In LITT, tract seeding progression occurs significantly faster than at the treated site, which may be associated with a worse overall prognosis. Prophylactic stereotactic radiosurgery to the LITT tract could be of benefit, however this may pose further risk to patients given the low overall frequency. More frequent monitoring may be necessary lesions in periventricular or difficult to ablate regions, or with longer LITT tracts.