A Study of the Gene Mutation Status in Cerebrospinal Fluid, Blood and Tumor Tissue of Non-small Cell Lung Cancer Patients With Brain Metastases

Primary lung cancer is one of the most common malignancies in China, with 57 percent of patients being diagnosed at advanced stage. At present, advanced lung cancer has entered the era of precise treatment. So it is very important to determine the gene mutation status of the tumor and prescribe drugs at the targets. Liquid biopsy is a suitable alternative when tumor tissues are difficult to obtain. Liquid biopsy technique refers to the use of human body fluid as a sample source to detect the information of related diseases, including blood, urine, saliva and cerebrospinal fluid. It is non-invasive, fast and simple, and can avoid the problem of insufficient sample size and support for repeated sampling to continuously monitor disease. With the increasing incidence of lung cancer and the development of diagnosis and treatment technology, the survival period of patients has been extended, and the incidence and diagnosis rate of the brain metastasis of lung cancer have increased year by year. The brain metastasis of lung cancer is the most common type of brain metastatic tumor. The incidence rate is about 40-50%, and the prognosis is poor--the natural median survival period is about 1-2 months. Because of the impractical intracranial tumor biopsy and very low level of DNA in peripheral blood, cerebrospinal fluid, which makes close contact with brain tumors, becomes potential available samples. Several studies have shown that genetic testing of cerebrospinal fluid is feasible. Therefore, this study aims to test the cerebrospinal fluid, blood and tissue by the latest second-generation sequencing technology at different time points, to dynamically monitor the gene mutation status of cerebrospinal fluid, blood and tissue, to explore the role of cerebrospinal fluid biopsy in the diagnosis and treatment of non-small cell lung cancer with brain metastases.