The Clinicopathologic Significance of a p63 Expression in Invasive Breast Cancer

Purpose: p63 is a recently described as p53 homologue. Despite their structural homologies, they have different activities. p63 is a specific myoepithelial cell marker in normal breast tissue and it is expressed in a minority of breast cancers. The aim of this study was to evaluate the prognostic significance of the p63 expression in breast cancer. Methods: The expression of p63 in breast cancer was determined by performing immunohistochemistry on 350 patients who underwent mastectomy at the Department of Surgery at Korea University Medical Center between January 1992 and September 2004. A retrospective analysis was conducted using the medical records. A tissue microarray was constructed, and immunohistochemical analysis for p63 was performed according to the usual methods. Results: Among 350 patients, 40 (11.4%) showed a p63 expression. There was a significant correlation between p63 and the histologic grade. There were significant correlations of p63 with p53 and HER2/neu, respectively. In the basal type of breast cancer, the p63 expression was significantly higher than in the luminal type of breast cancer. The 5 year disease free survival rates were 69% in the patients with a p63 expression and 76% in the patients without a p63 expression, but there was no statistical difference. Conclusion: The present results indicate that a p63 expression is associated with a high grade tumor, a p53 expression and a HER2/neu expression in breast cancer, which are the known poor prognostic factors of breast cancer. Immunohistochemical subtyping shows that the p63 expression is a useful predictor for the basal type of breast cancer. In addition, this study suggests that the p63 expression in the basal type of breast cancer is associated with a poor prognosis. (J Korean Surg Soc 2006;71:243-249)