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.