A preliminary study on the detection of lung cancer cells in pleural effusion by flow cytometry for non-small cell lung cancer

Abstract

Objective To investigate the clinical application value of flow cytometry (FCM) established by specific fluorescent monoclonal antibody in detecting lung cancer cells in pleural effusion with non-small cell lung cancer(NSCLC). Methods The FCM assay was established by using fluorescent monoclonal antibody NJ001 which could specifically recognize NSCLC. A case-control study was conducted to evaluate the level of lung cancer cells in pleural effusion among 32 cases of NSCLC (including 29 lung adenocarcinoma cases and 3 lung squamous cell carcinoma cases) and 26 cases of benign disease with definite diagnosis collected from the First Affiliated Hospital of Nanjing Medical University from February 2014 to August 2014. The data of FCM assay between NSCLC and benign disease were evaluated by the rank sum test. The data were analyzed by ROC curve to assess the diagnosis value. Those FCM results among 32 cases of NSCLC were compared with Papanicolaou staining by the chi-square test. Meanwhile, NJ001 specific antigen on exfoliate cells was detected by direct immunofluorescence assay and comparing with FCM assay by the chi-square test among 22 cases of NSCLC. Results The number of positive events by FCM assay was 5(0-18)/100 000 in benign pleural effusion and 100(2-988)/100 000 in pleural effusion of NSCLC, which was significantly higher compared with the benign disease (Z=-5.647, P<0.001). The area under the ROC curve was 0.934 and the optimal diagnostic critical value was 18/100 000. This method performed a high sensitivity[87.5% (28/32)] and specificity[100.0%(26/26)]. The positive rate in 29 lung adenocarcinoma cases was significantly higher by FCM assay than Papanicolaou staining[93.1%(27/29) vs 58.6%(17/29), χ2=7.627, P=0.006], and in 12 negative Papanicolaou staining lung adenocarcinoma cases the positive rate of FCM assay was 11/12; In 3 lung squamous cell carcinoma cases the positive rate of FCM assay was 1/3 while all of Papanicolaou staining presented negative results. The FCM assay positive rate of 22 NSCLC cases was significantly higher than the direct immunofluorescence assay[90.9%(20/22) vs 59.1%(13/22), χ2=4.364, P=0.037]. Conclusion The FCM assay established by specific fluorescent monoclonal antibody applied for lung cancer cells especially for lung adenocarcinoma detection in pleural effusion had a high sensitivity and specificity, which was confirmed to be a valuable technological application for NSCLC clinical diagnosis. Key words: Carcinoma, non-small-cell lung; Pleural effusion; Flow cytometry