Objective To investigate the relationship between the expressions of P-gp, GST-π and C-erbB-2 and clinicopathologic characteristics as well as prognosis in breast cancer. Methods The expressions of P-gp， GST-π and C-erbB-2 were detected by immunohistochemistry in 48 cases of breast cancer, and histopathologic characteristics as well as 5-year survival rate of these cases were analyzed. Results There was no significant difference in the expressions of P-gp and GST-π with age, histologic grade, number of lymph node metastasis and TNM stage of breast cancer ( P ＞ 0.05). There was significant difference in expression of C-erbB-2 with histologic grade, number of lymph node metastasis and TNM stage of breast cancer （ P ＜ 0.05）. Positive rate of P-gp expression in breast cancer with positive C-erbB-2 expression was remarkably higher than that in breast cancer with negative C-erbB-2 expression ( P ＜ 0.05) . Positive rate of GST-π and C-erbB-2 expression in survivals within 5 years was remarkably lower than that in deaths within 5 years ( P ＜ 0.01). Conclusion P-gp participates primary drug-resistance mechanism of breast cancer. The possibility of primary drug-resistance is higher in breast cancer with positive C-erbB-2 expression. The expression of C-erbB-2 helps to evaluate prognosis and the result of treatment in breast cancer.
