Among the many biological parameters of breast cancer, the p53 and HER-2/neu genes, which are located on the chromosome 17, and their gene products have been studied extensively by many researchers in regard their relation to the prognosis. The aim of this study was to evaluate the prognostic significance of the coexpression of p53 and HER-2/neu in breast cancer.

Formalin-fixed, paraffin-embedded tissues from 126 patients with invasive breast cancer were immunostained for p53 and HER-2/neu. Other prognostic parameters such as the patients' age, tumor size, lymph node metastasis, histologic grade, the presence of estrogen receptor (ER), and progesterone receptor (PgR) were evaluated. The patients' outcome was analyzed according to the expression of p53 and HER-2/neu as well as to the other prognostic factors.

Among the 126 patients, p53 and HER-2/neu were positive in 46 (36.5%) and 33 (26.2%) patients. According to the expression of p53 and HER-2/neu, the patients were classified into three groups; group 1: negative expression for both factors (n = 63), and group 2: positive expression for either one of the factors (n = 47), and group 3: positive expression for both factors (n = 16). The median follow-up period was 50 ± 11.1 months. On the Kaplan-Meier analysis, p53 and HER-2/neu were both related to the 5-year disease free survival rate (DFSR). Group 3 showed a significantly lower 5-year DFSR than did group 2 (66.2% vs. 85.2%, respectively, p = 0.05) and the group 1 (66.2% vs. 94.0%, respectively, p = 0.01). The multivariate analysis indicated that lymph node metastasis, ER, PgR, p53 and HER-2/neu expressions were significantly related to the patients' 5-year DFSR.

The expression of p53 and HER-2/neu was related to the 5-year DFSR of breast cancer, and the coexpression of p53 and HER-2/neu was found to have a more significant prognostic value than either one of these two parameters alone.