EGF and breast cancer: In another study, it was found that the levels of vascular endothelial growth factor, epidermal growth factor (EGF) and carcinoembryonic antigen in the saliva were significantly increased in patients with breast cancer.45 The levels of CA15-3 and c-erB-2 were also found to be increased in the saliva, which has positive correlations with the serum of patients with breast cancer.46 Based on these studies, potential salivary biomarkers can be applied to the early diagnosis of breast cancer.