GCDFP-15 and Mammaglobin Expression by Immunohistochemistry is of Limited Utility in Triple-Negative Breast Cancer

Aims In addition to estrogen and progesterone receptors, gross cystic disease fluid protein-15 (GCDFP-15) and mammaglobin (MAM) are the most common markers to identify breast origin by immunohistochemistry (IHC). GCDFP-15 expression has been reported in approximately 60% of breast carcinomas and MAM expression in approximately 80%. Data on their expression in triple-negative breast cancer (TNBC) are very limited. In this study, we examined the expression of these markers in TNBC to determine their utility in pathologic diagnosis.