Novel method for the detection and quantification of malignant cells in the CSF of patients with leptomeningeal metastasis of lung cancer

Abstract

Abstract. The aim of the present study was to discuss a novel method for the detection of malignant tumor cells in cerebrospinal fluid (CSF), by observing tumor marker-immunostaining fluorescence in situ hybridization (TM-iFISH) enrichment and by counting CSF malignant tumor cells in patients with lung cancer leptomeningeal metastasis (LM). A total of 10 CSF samples were collected from 6 patients that presented with lung cancer LM. For each patient, 20 ml CSF was obtained through a lumbar puncture, of which 7.5 ml was used to count the number of malignant tumor cells in the CSF using TM-iFISH enrichment. Cytological and biochemical examinations were conducted on the remaining 10 ml and 2.5 ml CSF, respectively. The 10 CSF samples were successfully analyzed by TM-iFISH, and the tumor cell count range was 3-1,823 cells/7.5 ml CSF in 7 of the samples detected. There were no tumor cells detected in the remaining 3 samples. Tumor cells were revealed in 3 of the samples through the CSF cytological examinations, and albumin protein levels were indicated to be greater than the normal range (normal range, 0.15-0.45 g/l), in 9 of the samples using CSF biochemical examinations. Additionally, TM-iFISH was performed again to count the CSF malignant tumor cells in 3 of the patients following intrathecal injection of chemotherapy (methotrexate 10 mg and dexamethasone 5 mg). The results indicated that the malignant tumor cell count of 2 of the patients had decreased in comparison to the pre-treatment cell count. As it is capable of enriching and counting CSF malignant tumor cells in patients with lung cancer LM, TM-iFISH may be an effective method to diagnose lung cancer LM and to evaluate its efficacy.