ERBB2 and breast carcinoma: In this regard, we investigated these ten markers (EGFR2, CA15-3, CA27.29, MCA, CEA, CA125, CA19-9, CYFRA 21-1, ferritin, and CRP) in saliva with the aim of their possible use for the differential diagnosis of HER2-positive and HER2-negative subtypes of breast cancer.