Epidermal Growth Factor Receptor Mutation Detection in Cerebrospinal Fluid of Lung Adenocarcinoma Patients with Leptomeningeal Metastasis

Background: Epidermal growth factor receptor (EGFR) mutations are associated with leptomeningeal metastases (LM) of nonsmall cell lung cancer and sensitivity to tyrosine kinase inhibitor (TKI) treatment. Owing to the difficulty of obtaining carcinomatous meningeal tissue for analysis, cerebrospinal fluid (CSF) might be an alternative. Objective: To investigate the EGFR mutation detection in the CSF of lung adenocarcinoma patients with LM. Methods: Twenty-five lung adenocarcinoma patients with LM diagnosed by CSF cytology were retrospectively evaluated. The results of EGFR mutation detection in CSF, the treatment plan, and clinical outcome information were recorded. Results: Nineteen patients had a known EGFR status in their primary tumors. Twenty patients received EGFR mutation analysis in CSF after LM diagnosis and 14 of them with a known EGFR mutation status of both primary tumors and CSF. Ten (71.4%) had the same EGFR gene status. In primary tumors, no T790M mutations were detected, whereas in CSF, 2 L858R cases and 1 19del case had T790M mutations at the same time. The detection rate of T790M mutations in CSF was 18.1% (2 of 11) in all cases with EGFR-sensitive mutations in the primary lesion. Conclusions: EGFR mutation detection in CSF of lung adenocarcinoma patients with LM might be an alternative when leptomeningeal biopsy cannot be applied and may help to guide TKI treatments.