The therapeutic value of cerebrospinal fluid ctDNA detection by next-generation sequencing for meningeal carcinomatosis: a case report

BACKGROUND: It is usually very complicated to treat meningeal carcinomatosis, and it is important to treat it as soon as possible. CASE PRESENTATION: The 19-Del mutation was found in the exon for the epidermal growth factor receptor gene in the pleural effusion of a patient on March 11th, 2015. He took 250 mg of oral gefitinib once a day for 11 months beginning in December of 2015. On the 3rd of November 2016, he arrived at the hospital and presented with dizziness, headache and transient blurred vision. At this time, he began to take 4 mg of oral zoledronic acid once a month to prevent bone metastases. The result of a cytology exam of the cerebrospinal fluid showed that the man had meningeal carcinomatosis. The 19-Del mutation and the 20-T790 M mutation in the exon of the epidermal growth factor receptor gene was found by the next generation sequencing of the CSF. Then, he discontinued taking gefitinib and began to take 90–100 mg of oral AZD9291 once a day in November 2016. After adjusting the medication dose based on the NGS, his headache was noticeably reduced, and his condition gradually stabilized. CONCLUSIONS: Cerebrospinal fluid ctDNA detection by next generation sequencing may become a suitable biomarker to monitor clinical treatment response in meningeal carcinomatosis.