The aim of the work is to study the metabolic characteristics of saliva in lung cancer for use in early diagnosis and determining the prognosis of the disease. The patient group included 425 lung cancer patients, 168 patients with non-cancerous lung diseases, and 550 healthy volunteers. Saliva samples were collected from all participants in the experiment before treatment and 34 biochemical saliva parameters were determined. Participants were monitored for six years to assess survival rates. The statistical analysis was performed by means of Statistica 10.0 (StatSoft) program and R package (version 3.2.3). To construct the classifier, the Random Forest method was used; the classification quality was assessed using the cross-validation method. Prognostic factors were analyzed by multivariate analysis using Cox’s proportional hazard model in a backward step-wise fashion to adjust for potential confounding factors. A complex of metabolic changes occurring in saliva in lung cancer is described. Seven biochemical parameters were identified (catalase, triene conjugates, Schiff bases, pH, sialic acids, alkaline phosphatase, chlorides), which were used to construct the classifier. The sensitivity and specificity of the method were 69.5% and 87.5%, which is practically not inferior to the diagnostic characteristics of markers routinely used in the diagnosis of lung cancer. Significant independent factors in the poor prognosis of lung cancer are imidazole compounds (ICs) above 0.478 mmol/L and salivary lactate dehydrogenase activity below 545 U/L. Saliva has been shown to have great potential for the development of diagnostic and prognostic tests for lung cancer.

This research was aimed at a search for regularities in changes to parameters of endogenous intoxication and saliva lipid peroxidation in patients with lung cancer, non-malignant lung diseases, and apparently healthy people. All patients went through saliva sampling at an amount of 1 mL. A concentration of malondialdehyde (MDA) was measured according to a reaction with thiobarbituric acid, and a level of middle molecules (MM) was measured with UV spectroscopy at 254 and 280 nm, while the content of lipid peroxidation products was measured according to a degree of heptane extract light absorption at wavelengths of 220, 232, 278, and 400 nm. It has been revealed that in the context of lung cancer, the level of diene conjugates decreases, increasing the level of triene conjugates, Schiff’s bases, and MM. As a tumor grows, there is a decrease in the level of lipid peroxidation primary products and an increase in endotoxemia phenomena. The process is more apparent when going from local to locally advanced disease states. The nature of the MDA change is nonlinearly associated with tumor progression. The findings might be used to optimize traditional aids of diagnostics, in disease state forecasting, in treatment monitoring, etc.

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Background: Recently, the attention of researchers to the study of the properties of human saliva, as a material with unique properties and diagnostic capabilities, has increased. Research objective: to study the connection of the biochemical composition of saliva and blood plasma in the norm, depending on gender and age. Methods: 107 volunteers took part in the study, including 46 female (37.2 ± 3.9 years old) and 61 male (36.1 ± 2.8 years old). In all samples of saliva and blood plasma, 16 biochemical parameters were determined, including mineral and protein composition, enzyme activity. Non-parametric statistical methods were used to process the data. Results: It has been shown that it is difficult to establish an unambiguous relation between biochemical parameters of saliva and blood plasma. The calculation of the Spearman correlation coefficients showed that only 7 of the 16 parameters demonstrate the presence of a weak correlation between the content in saliva and plasma. Conclusion: In general, the determination of the composition of saliva may have an independent diagnostic value; in this case, drawing a parallel with the composition of serum and blood plasma is not advisable. Nevertheless, the use of saliva in clinical laboratory diagnostics is associated with the need to establish criteria for the norm and pathology for each biochemical parameter.

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