BACKGROUNDTo investigate the clinical possibility of detection of lung cancer cells in the peripheral blood with cytokeratin and 2F7/S5A monoclonal antibody by flow cytometry (FCM) in patients with lung cancer.

METHODSFive mililiter peripheral blood was collected. The mononuclear cells were isolated by Ficoll-Hypaquegradient centrifugation. Then the cells were labeled with lung specific antibody (2F7/S5A) and antibodies against CD45, cytokeratin (CK). The quantitation of CD45 -CK +2F7/S5A + cells were performed by FCM.

RESULTSA total of 151 people were studied, including 20 healthy controls, 116 patients with lung cancer and 15 patients with benign pulmonary diseases. The phenotype of monocytes of peripheral blood was CD45 +CK -2F7/S5A -, while the phenotype of lung cancer cells was CD45 -CK +2F7/S5A +. No cancer cell was found in peripheral blood of all the healthy controls. One out of 15 cases of benign pulmonary diseases was found to have CD45 +CK -2F7/S5A - cells in peripheral blood. And 39 out of 116 patients with lung cancer were found to have circulating lung cancer cells. The sensitivity, specificity, positive predictive value and negative predictive value of detection was 33.62% , 93.33%, 97.50% and 15.38%, respectively. The average quantitation of circulating cancer cell detected was 0.12×10⁶/L.

CONCLUSIONSThere is high specificity and positive predictive value of the examination of circulating cancer cells in patients with lung cancer by FCM, which could detect trace cancer cell in peripheral blood of lung cancer. It may be valuable in diagnosis and treatment of lung cancer.