Salivary protein biomarkers are known to be useful for discriminating between healthy controls, fibroadenomas and incipient ductal carcinoma lesions [224], and lymph-node-positive and lymph-node-negative patients with ductal carcinoma [225], as well as to assess the differences between the salivary protein profiles of HER2/neu-receptor-positive and HER2/neu-receptor-negative patients [226]. This evidence concerns the gene ERBB2 and breast ductal adenocarcinoma.