Abstract: Abstract：Objective To assess the value of tumor marker immunostaining-FISH (TM-iFISH) technology on concen⁃ trating and enumeration of tumor cells in CSF of lung cancer patients with leptomeningeal metastasis(LM). Methods Six cases of non-small cell lung cancer with leptomeningeal metastasis, which were diagnosed by CSF cytology or enhanced MRI scan, were selected. A total of 20 mL of CSF was collected in each case. TM-iFISH technology was employed to concen⁃ trate and quantify circulating tumor cells in 7.5 mL CSF samples in each case while CSF cytology used 10 mL CSF samples in each case; Finally, the rest 2.5 mL CSF in each case was used for biochemistry assay. Results Ten CSF samples from 6 patients with non-small lung cancer with LM were assayed and tumor cells numbers ranging between 3 and 1 823 every 7.5 mL were found in 7 samples. On the other hand, CSF cytology examination only revealed tumor cells in 3 cases. Using CSF biochemical assay, higher than normal of protein level was found in 9 cases. TM-iFISH technology was employed again in 3 cases of patients who received treatment. Tumor cell count in CSF reduced in 2 out of the 3 cases. Conclusion TM-iFISH technology is a new method for detection and enumeration of tumor cells in the CSF in non-small cell lung cancer patients with leptomeningeal metastasis. This technology present diagnosis and curative values in lung cancer patients with leptomen⁃ ingeal metastasis.

Key words: meninges；carcinoma, non-small-cell lung；neoplasm circulating cells；leptomeningeal metastasis, nonsmall cell lung cancer；cerebrospinal fluid；tumor marker immunostaining-FISH