Hormonal receptors expression in epithelial cells of mammary phyllodes tumors correlates with pathologic grade of the tumor: A multicenter study of 143 cases

We used immunohistochemical analysis to detect the presence of estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR) protein expression in the epithelial and stromal cells of 143 phyllodes tumors (PTs). Expression of epithelial ER and PR proteins was common, occurring in 43% to 84% of PTs. Expression of epithelial AR protein and stromal ER, PR, and AR proteins was low (5% or less) in all tumors. An inverse relationship of epithelial ER and PR protein expression with degree of malignancy in PT was found (P < .05), and ER expression also correlated with mitotic count (P < .05). When considering PT with the expression of ER or PR proteins and the coexpression of both, the inverse relationship with tumor grade also was significant (P < .05). As the hormonal receptor protein expression shows a consistent decrease with increasing malignancy, we infer that the epithelium has a crucial role in the pathogenesis or progression of PT.