Metabolic Features of Saliva Before and After Breast Cancer Surgery

Background: Changes in salivary metabolites in patients after surgery can provide important information for fundamental research. Objectives: To analyze changes in the salivary metabolic profile before and after breast tumor surgery. Methods: The study involved 660 breast cancer patients (54.6 ± 1.9 years) and 127 healthy volunteers (49.3 ± 1.5 years). Saliva samples were collected from all patients before treatment, and levels of total protein, urea, α-amino acids, imidazole compounds, and nitric oxide, as well as gamma-glutamyl transferase (GGT), lactate dehydrogenase (LDH), α-amylase, and catalase activity, were determined. In 139 breast cancer patients, these parameters were re-measured in saliva 4 weeks after surgical removal of the tumor (radical mastectomy). Results: In breast cancer, the activity of GGT (+17.6%, p < 0.0001), catalase (+14.7%, p = 0.0485), urea content (+24.6%, p = 0.0006), total protein (+13.6%, p = 0.0432), α-amino acids (+3.1%, p < 0.0001) increased in saliva, but LDH activity (-16.9%, p < 0.0001) and the content of imidazole compounds (-25.2%, p < 0.0001) decreased. It was found that after surgical treatment of breast cancer, a number of the biochemical parameters of saliva are restored. It is shown that the greatest deviations of the metabolic profile of saliva from the norm before surgery correspond to the early stages and the most prognostically favorable phenotypes of breast cancer. After surgery, metabolic differences are most pronounced for triple-negative breast cancer. Conclusions: A time interval of 4 weeks is not sufficient for complete recovery, but for most biochemical parameters the values are intermediate between those for healthy controls and primary breast cancer.