SURG-52. Predictors of leptomeningeal disease after brain metastasis resection and laser interstitial thermal therapy

Abstract Leptomeningeal disease (LMD) is a highly morbid consequence of CNS metastasis. Preoperative stereotactic radiosurgery (preSRS) has recently been promoted to prevent leptomeningeal tumor seeding during surgery. We accordingly sought to quantify the rate of LMD at a high volume center for both resection and laser interstitial thermal therapy (LITT). We retrospectively reviewed 390 patients undergoing treatment of brain metastases with a single surgeon. Patients underwent resection (n = 249, mean = 1.10 surgeries/patient, mean survival = 597 ± 657d, 37% surviving), LITT (n = 106, mean = 1.07 surgeries/patient, mean survival = 440 ± 525d, 37% surviving), or both (n = 3 simultaneous, n = 32 staggered, mean = 2.06 surgeries/patient, mean survival = 752 ± 774d, 51% surviving). LMD was defined as diffuse leptomeningeal enhancement on MRI. Patients with pre-operative LMD (n = 5) were excluded from incidence analysis. The overall incidence of postoperative LMD was low across surgical modalities (resection: 6.4%, LITT: 5.7%, both: 8.6%; χ² = 0.37, p > 0.05). Cumulative LMD incidences (censoring unaffected patients at time of death) produced 5-year rates of 11.9% (13/109) for resection, 6.9% (4/58) for LITT, and 17.7% (3/17) for both (p > 0.05, pairwise Fisher’s tests). Infratentorial tumors exhibited a higher but non-significant LMD incidence than supratentorial tumors (11.4% vs 5.8%, p = 0.18). Primary tumor site was significantly associated with LMD overall incidence (χ² = 22.34, p = 0.002), with the highest rate from breast (17.5%, 11/63) and lung (5.7%, 11/194) cancers. These findings suggest that selection of resection versus LITT for treatment of brain metastases should be directed by tumor characteristics and shared decision making. Conversely, the nuances of surgical technique may influence LMD development. Future prospective studies are warranted to validate these findings and clarify the role of emerging approaches such as preSRS in mitigating LMD.