Oxidative stress plays a key role in breast cancer progression. However, little is still known about the relationship between the mutation, the incidence of breast cancer and oral homeostasis. This is the first study to evaluate the secretory function of salivary glands, biomarkers of redox balance, and oxidative damage to proteins and lipids in the saliva of subjects with the mutation. Ninety eight women were enrolled in the study and allocated to four groups based on molecular DNA testing: generally healthy patients without the mutation, patients with breast cancer but without the mutation, generally healthy patients with the mutation, and patients with both breast cancer and the mutation. We demonstrated that saliva from breast cancer patients with the mutation is characterized by enhanced antioxidant capacity and a higher degree of oxidative damage to proteins and lipids. The mutation can cause a predisposition to early salivary gland dysfunction, both in patients with breast cancer and in healthy individuals, leading to a decrease in salivary proteins. Using cluster analysis, we showed that salivary peroxidase, advanced glycation end-products (AGE), total antioxidant status (TAS) and malondialdehyde (MDA) may have particular clinical significance in non-invasive diagnostics of breast cancer.