Lactate dehydrogenase as a prognostic marker in neoplastic meningitis.

This study aimed to establish the prognostic utility of lactate dehydrogenase (LDH) levels in the cerebrospinal fluid (CSF) of patients with neoplastic meningitis (NM). Patients with a confirmed diagnosis of NM at a cancer referral center were included. Data on demographic and oncological background, clinical symptoms, diagnostic tests, treatment, and survival were analyzed. In total, 119 patients were included, 74% of whom were females. The mean age was 44.2 years at the time of cancer diagnosis and 46.6 years at the time between NM diagnosis. Primary cancers were mostly breast cancer, lung cancer, or hematologic malignancies. The mean Karnofsky performance score (KPS) was 65. Frequent clinical symptoms were visual complaints, headache, cranial neuropathy, focal weakness, and decreased awareness. Diagnosis was made based on clinical symptoms, cytological CSF analysis results, and/or magnetic resonance imaging findings. The median overall survival (OS) was 4 months (95% CI 2.48-5.52). Prognostic variables associated with a better OS were hematopoietic malignancies, KPS ≥ 70, absence of meningeal signs, receiving any form of treatment, normal CSF glucose levels, and normal CSF LDH levels. After bivariate analysis, high LDH in the CSF remained statistically significant as a poor prognostic indicator. The LDH level is a useful parameter to assess the prognosis of patients with NM. Other factors associated with the prognosis of these patients were tumor type, CSF glucose levels, performance status, and receiving any form of treatment.