Serum sialic acid in malignant tumors, bacterial infections, and chronic liver diseases.

The total serum sialic acid concentration was determined in 2,264 persons with various malignant tumors, bacterial infections, rheumatic diseases, and chronic liver diseases, and in a control group. The thiobarbiturate method according to Warren was used. The upper limit (95% percentile) in the control group was 2.23 mumol/ml. Higher values were found in the groups with neoplasms (mean: 3.04 mumol/ml), inflammatory diseases (e.g., pneumonia: 3.02 mumol/ml), and active rheumatoid arthritis (3.05 mumol/ml). In the group with malignant diseases, the sialic acid concentration at the time of diagnosis was highest for bronchial carcinoma (3.29 mumol/ml) and lowest for breast cancer (2.58 mumol/ml). In chronic liver diseases the mean sialic acid level was lower than in a heterogeneous group of noninflammatory and nonneoplastic diseases. The estimation of the serum sialic acid concentration could be useful in the detection of tumor burden and metastases, and in the evaluation of the later course and prognosis of malignant neoplasms if bacterial/inflammatory and active rheumatoid processes can be excluded.