Background and Objectives: Phyllodes tumor (PT) is a biphasic tumor with unpredictable behavior. Our study aimed to evaluate clinicopathologic factors and biomarkers that may be helpful in predicting the outcome of these tumors. Methods: We evaluated immunoreactivity of p53, c-erbB-2, and Ki-67 in 23 PT treated over a 10-year period. The proliferative activity in PT and expression of p53 and c-erbB-2 were correlated with clinicopathologic features of the tumors and patients' outcome. Results: Positive stromal p53 immunoreactivity was found in PT with atypia, infiltrative borders, high cellularity, as well as in PT that displayed higher then average proliferation index, although none of these parameters reached statistical significance. There was a good correlation between proliferative stromal cell activity expressed Ki-67-labeling index and the malignant features of the tumors. Primary tumors that recurred displayed high proliferative activity. Three of four recurrent tumors showed a progression toward higher malignant phenotype with concomitant increase in proliferative stromal cell activity, c-erbB-2-positive tumors had no particular histologic features or association with either p53 positivity or higher proliferative indices. Conclusions: p53 expression tends to be more frequent in PT with higher malignant potential but did not predict recurrence. Incompletely excised tumors that recurred displayed high proliferative activity in their primary tumors. Progression toward more malignant phenotype in the recurrent PT was accompanied with increase in stromal cell proliferative activity, suggesting the presence of biological continuity between benign, borderline, and malignant PT.
- Phyllodes tumor