[Serum lipid-bound sialic acid as a marker in lung cancer patients]

To evaluate the usefulness of serum lipid-bound sialic acid (LSA) as a tumor marker in patients with lung cancer, its serum levels were determined in 85 patients with primary lung cancer, 42 patients with benign pulmonary diseases and 22 healthy controls by the method developed by Katopodis and Stock. The mean serum LSA concentration was significantly higher in the patients with primary lung cancer [32.4 +/- 16.4 (SD) mg/dl] than that in the patients with benign pulmonary diseases (22.4 +/- 12.4 mg/dl) or in healthy controls (17.2 +/- 4.5 mg/dl). The serum LSA level was elevated above the mean value plus 2 SD for the healthy controls (26.0 mg/dl) in 60% of all cases with primary lung cancer including 1 of 9 (11.1%) in stages I and II and 50 of 76 (65.8%) in stages III and IV and 35.4% of the patients with benign pulmonary diseases. No significant difference was observed in serum LSA concentration among each cell type of lung cancer. Serum carcinoembryonic antigen (CEA) was elevated (greater than 5.0 ng/ml) in 39.8% of the patients with lung cancer. As there was poor correlation between serum LSA and CEA levels, when these two markers were used in combination, 71.1% of the cases with lung cancer in this study showed elevated levels of either serum LSA or CEA, or both. Moreover, in the patients with small cell lung cancer followed up during intensive chemotherapy, serum LSA levels changed almost parallel with the clinical course. These results indicate that serum LSA may be a useful biochemical marker in lung cancer patients.