Significance of an epidermal growth factor receptor mutation in cerebrospinal fluid for leptomeningeal metastasis and successful treatment with osimertinib: A case report and literature review

摘要

Leptomeningeal metastasis (LM) is associated with poor prognosis; in cases of LM from non-small cell lung cancer (NSCLC), an improvement in prognosis can be expected if molecular targeted drugs are available. Gefitinib, a first-generation epidermal growth factor receptor (EGFR)- tyrosine kinase inhibitor (TKI), and erlotinib, a second-generation EGFR-TKI, are more effective than conventional treatment for LM from EGFR-mutation-positive NSCLC [1]. Moreover, osimertinib, a third-generation EGFR-TKI with good central nervous system penetra- tion, is more effective for treating LM from EGFR mutation-positive NSCLC [2,3]. Therefore, it is important to determine whether osi- mertinib can be used in the treatment of LM. We report a case of LM where detecting an EGFR mutation in the cerebrospinal fluid (CSF) was useful in the diagnosis and treatment of lung cancer and review the related literature.