[Evaluation of sialyl SSEA-1 antigen in patients with lung cancer]

Stage-specific embryonic antigen-1 (SLX) is a glycolipid recognized by a monoclonal antibody (FH 6) which is produced by cells immunized with mice teratocarcinoma cell line. Using an SLX (Otsuka) kit from Ostuka Assay Laboratory, we measured the serum level of SLX in 96 patients with lung cancer, 305 patients with non-cancerous lung disease and 86 healthy adults, prospectively. When we adopted a cutoff level of 42U/ml (mean + 2S.D. in the healthy adults), the overall positive rates were 29.2% in the lung cancer patients, 15.1% in the non-cancerous patients and 0% in the healthy adults. The positive rate of the lung cancer patients was significantly higher than in the patients with non-cancerous lung disease (p less than 0.05). According to the histological type of lung cancer, the positive rates were 40.9% in 44 patients with adenocarcinoma, 18.4% in 37 patients with squamous cell carcinoma, 0% in 7 patients with small cell carcinoma, and 0% in 3 patients with large cell carcinoma. Staging of the lung cancer patients revealed positive rates for serum SLX of 5.6% in 18 stage I patients, 22.2% in 9 stage II patients, 33.3% in 21 stage IIIA patients, 33.3% in 27 stage IIIB patients, 42.9% in 21 stage IV patients. After we performed the immunostaining method for SLX using FH6, positive immunoactivity was demonstrated mainly in the cell membrane of adenocarcinoma cells. SLX seems to be a tumor-associated marker in patients with lung adenocarcinoma.