Potential Diagnostic Significance of Salivary Copper Determination in Breast Cancer Patients: A Pilot Study.

Determination of the copper content in the saliva of breast cancer patients was carried out to assess the potential diagnostic and prognostic value. The malignant group included 75 breast cancer patients; the benign group included 87 patients with fibroadenomas; and the control group included 20 volunteers without breast pathology. All participants had 1 ml of saliva collected prior to treatment. The determination of copper in saliva was carried out by the stripping voltammetric method. Overall survival was assessed using the Kaplan-Meier method with the presentation of survival curves and the calculation of the significance of differences by Log-rank. The average copper content in the saliva of breast cancer patients is 49.3% higher than in patients with fibroadenomas and 60.4% higher than in volunteers without breast pathologies. Within the group of breast cancer patients, the content of copper in saliva is heterogeneous, which limits the possibilities of using this indicator for diagnostic purposes. The copper content increases when comparing the initial stages and locally widespread (+ 22.4%) and then sharply increases by 3.5 times at the T3-4 N0-2 M0 stage. For HER2-positive breast cancer, the copper content in saliva is 51.9% higher than for HER2-negative, a similar pattern was observed for luminal A and B breast cancer subtypes. The content of copper in saliva less than 1.14 mg/l is a prognostically unfavorable sign, while the relative risk of dying from breast cancer more than doubles. Thus, the content of copper in saliva can be used in clinical practice for planning treatment tactics.