Indicators of L-arginine metabolism in saliva: a focus on breast cancer.

OBJECTIVES: To analyze the arginase activity, the level of nitric oxide (NO) and the cytokine profile of saliva in patients with breast cancer.

METHODS: A total of 114 volunteers took part in this case-control study, and were divided into three groups as follows: The main group (breast cancer, n = 43), the comparison group (fibroadenomas, n = 32), and the control group (conditionally healthy, n = 39). All participants underwent biochemical examination of saliva and histological verification of the diagnosis.

RESULTS: We found that the arginase activity in the saliva of breast cancer patients was significantly higher, and the level of NO was lower than in the control group. The 'arginase:NO' ratio was found to be 0.22 for the control group, 0.98 for the comparison group (p = 0.0040), and 1.48 for the breast cancer group (p ˂ 0.0001). The maximum increase in the 'arginase:NO' is characteristic of the early stages of the disease, which makes this ratio potentially applicable for the diagnosis of breast cancer with sensitivity and specificity of 81.1% and 81.0%, respectively. It was not possible to establish an unambiguous relationship between the level of cytokines and the metabolic parameters of L-arginine. However, we found an increase in salivary cytokine levels in breast cancer, and thus may represent an independent direction of research.

CONCLUSIONS: Saliva can be used as a substrate to determine L-arginine metabolic parameters.