Clinical significance of P-glycoprotein expression in metastatic breast carcinoma

Objectives: To evaluate the expression of P-glycoprotein (P-gp) and it's effect on chemotherapy response in metastatic breast carcinoma. Methods: 46 postoperative patients with metastatic breast carcinoma were enrolled. P-gp expression was detected by SABC immunohistochemical method. These patients were treated with combined chemotherapy of cyclophosphamide, pirarubicin and 5-fluorouracil for at least two cycles. The relationship between P-gp expression and chemotherapeutic response was analyzed. Results: The positive rate of P-gp expression was 56.5%, the P-gp expression in the patients with lung or liver metastasis was higher than that in patients with skin or lymph node metastasis (P=0.049). The overall response rate was 58.1% in 43 patients; the response rate (89.5%) of the P-gp negative group was higher than that (30.0%) of the P-gp positive group (P<0.01). The response rate (87.5%) in the patients with skin or lymph node metastasis was higher than that (40.7%) in the patients with lung or liver metastasis (P<0.05). In the postoperative patients who had received CAF or CMF regimen adjuvant chemotherapy previously, the response rate of metastatic diseases to chemotherapy had no significant difference (71.4% and 37.5%, respectively) (P=0.052). Conclusion: Patients with metastatic breast carcinoma had higher P-gp expression and these patients should be treated with non-MDR drugs chemotherapy.