Sialic Acids of Saliva in Primary and Differential Diagnosis of Lung Cancer

Abstract

The aim of the study was to explore the option of using sialic acid of saliva as a marker for primary and differential diagnosis of lung cancer.Materials and Methods. The study included 1903 subjects divided as follows: the main group (lung cancer, n=337, and nonmalignant lung diseases, n=108), the comparison group (other types of oncological diseases, n=1033), and the control group (generally healthy, n=425). All participants filled the medical questionnaires and presented the histological verification of their diagnoses; then they underwent biochemical examination of their saliva samples. The level of sialic acids and the content of mucin in the saliva were determined spectrophotometrically.Results. We found that the average level of sialic acids in the control group (0.270±0.037 mmol/L) was significantly higher than that in lung cancer (0.138±0.006 mmol/L) or non-tumor diseases of the lungs (0.148±0.003 mmol/L). The saliva content of sialic acids did not significantly differ between various histological types of lung cancer (0.175±0.027 and 0.166±0.024 mmol/L for squamous cell lung cancer and adenocarcinoma, respectively). We also noted that in patients with metastatic lung cancer, the level of sialic acids in the saliva was the lowest as compared with the generally healthy subjects.Conclusion. The level of sialic acids in the saliva decreases both in patients with lung cancer and in patients with non-malignant lung diseases. These results rationalize the option of using this parameter for the primary diagnosis of lung disorders as a whole; however, for the differential diagnosis of various lung diseases, the level of saliva sialic acids is of little value.