Paraneoplastic neurological syndrome (PNS) is a clinical syndrome that affects the central nervous system, peripheral nerves, neuromuscular junctions and muscles by the distant influence of the tumor. No tumor cells are visible in the neuropathy. The disease is a rare clinical syndrome, and lung cancer is the most common type of tumor that causes PNS.If PNS can be diagnosed when there are no tumor symptoms, not only can the cause of PNS be identified, but early tumors can be found for treatment time, and measures can be taken in the early stages of the tumor to improve survival. Tumor free DNA (cell-free DNA, cfDNA) methylation detection is to determine the cancer condition and cancer type of the subject by detecting the methylation of free DNA released by tumor cells. In normal cells, tumor suppressor genes are expressed and proto-oncogenes are silenced; in tumor cells, tumor suppressor genes are hypermethylated and silenced, and oncogenes are hypomethylated and activated. The release of free DNA into the blood will be quickly cleared in tens of minutes to several hours, which can reflect the body's cell damage in real time, and is of great significance for monitoring the early occurrence and development of the disease. At present, the sensitivity of lung cancer cf-DNA detection technology is close to 100%, and the specificity is 94%, which is an effective detection technology for early detection of lung cancer.
The purpose of this study is to verify whether the cell-free DNA of lung cancer in the blood can be used as a biomarker for early diagnosis and prognosis evaluation of patient with paraneoplastic syndrome of the nervous system.