OBJECTIVETo evaluate the effect of vascular endothelia1 growth factor (VEGF) on the hematogenous metastasis of non-small cell lung cancer (NSCLC).

METHODSThe identification of lung cancer cells in the peripheral blood were carried out by cytological, immunohistocytologica1 and immunofluorecent stains respectively, following isolation of cytokeratin-expressing cells with magnetic activated cell sorting. The quantification of cancer cells in the blood was performed according to the established flow cytometric assay. The plasma VEGF was measured by commercially available ELISA kit.

RESULTSThe lung cancer cells in the blood, showing a remarkable nuclear polymorphism, expressed the epithelial marker cytokeratin and telomerase reverse transcriptase (hTERT). These cells were stained positive by an NSCLC-specific monoclonal antibody S5Al0-2, but negative by antibodies against CD34 and CD45 antigens. Using the flow cytometric assay, 44 cases (28.6%) of l54 NSCLC patients were found to have cancer cells in their blood, with the incidence of positive cases correlated with the stage of disease. The plasma VEGF level was significantly increased in NSCLC patients in comparison with healthy individuals and patients with benign pulmonary diseases. This level was correlated with the stages of disease in patients with adenocarcinoma. In patiens with cancer cells in their blood, a higher level of plasma VEGF was related with an increased number of cancer cells.

CONCLUSIONThe plasma VEGF level is increased in NSCLC patients with approximate1y one fourth to have cancer cells in the peripheral blood. In these patients, increased VEGF level promotes hematogenous tumor metastasis, as indicated by a much higher number of cancer cells in the blood.