The Likelihood of Developing Leptomeningeal Metastasis (LM) in Cancer Patients with Neurological Symptoms but Negative Neuroimaging and CSF Cytology (P4.237)

Objective: This study characterizes the clinical outcome of cancer patients with initial negative MRI and CSF evaluation for Background: Improved systemic disease control and prolonged survival have led to increased recognition of LM. However, diagnosis remains difficult. We examined how many patients with clinically-suspected LM develop proven LM after negative CSFcytology and neuroaxis imaging. Methods: We identified patients with solid tumors and neurological symptoms suspicious for LM seen by neurologists at MSKCC from April 2013 to July 2015 and whose CSF was collected prospectively in our CSF bank. For inclusion, all patients must have undergoneCSF cytology and neuroimaging and have at least 1 month follow up. Results: 82 patients were enrolled (27 breast, 24 lung, 7 melanoma, 6 GYN, 5 GU, and 13 other). Of those, 56 (68[percnt]) had brain metastasis. 19 had no further evaluation, 12 of whomdied and 7 remain alive. 63/82 patients (77[percnt]) had follow up neuroimaging, 23 of whom also had follow up CSF cytopathological analysis. A total of 9/63 patients (14[percnt]) were diagnosed with LM on follow up tests: 3 by neuroimaging alone, 3 CSF alone, and 3 with positive CSF cytology and neuroimaging. Diagnosis of LM wasmade a median of 5 months after initial LM evaluation. Overall survival from initial lumbar puncture was 12.1 months (range 0.9-29.1 months). Conclusions: Our study suggests that initial negative workup of LM portends only a small likelihood of developing LM, supporting the conclusion that patients with suspected LM with negative CSFcytology and neuroimaging may be followed clinically. Further evaluation should be reserved for patients who develop new or progressive neurologic symptoms. Prospective studies are required to evaluate the true incidence of LM in patients with cancer and to determine its effect on survival. Disclosure: Dr. Haggiagi has nothing to disclose. Dr. Lin has nothing to disclose. Dr. Briggs has nothing to disclose. Dr. Shagabayeva has nothing to disclose. Dr. DeAngelis has received personal compensation for activities with Juno Therapeutics as a member of the Medical Advisory Board. Dr. Boire has nothing to disclose. Dr. Pentsova has nothing to disclose.