ER, p53 and MIB-1 are significantly associated with malignant phyllodes tumor.

Fibroadenomas (FA) are common while phyllodes tumors (PT) are rare and both tumors are composed of epithelial and stromal components. We evaluated the expression status of ER, Bc12, p53, and MIB-1 protein in these tumors. One hundred and ninety-three tumors comprising of 117 FAs and 76 PTs were examined using immunohistochemistry on tissue microarray. The mean age of patients with FA was 28.5 years while the mean ages of patients with benign, borderline and malignant PTs were 41.7, 48.6 and 42.1 years, respectively. Also all types of PTs were large (>Scm). ER showed a strong nuclear staining in the epithelial component of all tumors while ER/3 immunoreactivity was detected in both the epithelial and stromal components ofF A and PT. ER/β (p<0.001), and p53 (p=0.006) in the stromal component were associated with tumor size. p53 expression was significantly associated with both the epithelial and stromal components of malignant PTs (p<0.05). In the PT, the decreased expressions of p53 and MIB-1 were significantly different with positive Bc12 protein expression in the epithelial component (p=0.000). In addition, MIB-1 was also found to be associated with ER and ER/3 in the stromal component (p=0.000). The expression of p53 with tumor size and histological grade in PT may increase the risk for malignancy.