[Influence of P-glycoprotein expression on chemotherapeutic response of metastatic breast carcinoma].

Background & Objectives: The clinical study showed that the P-glycoprotein(P-gp) expression was closely associated with the chemotherapeutic effect, response rate, prognosis, and survival time. Until now, few clinical papers have reported about metastatic sites and its response to chemotherapy with P-gp expression in metastatic breast carcinoma. The current study was designed to investigate the role of P-gp expression and its clinical value of chemotherapy for the patients with different metastatic sites of this carcinoma.

Methods: P-gp expression in 46 postoperative patients with metastatic breast carcinoma was detected by SABC immunohistochemical method. 43 cases treated with combination regimen: Cyclophosphamide 600 mg/m2 i.v. on day 1, Pirarubicin 60 mg/m2 i.v. on day 1, 5-Fluorouracil 600 mg/m2 i.v. on days 1 and 8. Repeat the cycle every 3 weeks for at least 2 cycles. The correlation between P-gp expression and chemotherapeutic response was analyzed.

Results: 1) P-gp expression positive rate was 56.5%, the P-gp expression in the patients with lung or liver viscera metastasis was higher than that in skin or lymph node metastasis (P = 0.049). 2) The overall response rate was 58.1% in 43 patients. The response rate of the P-gp negative group was higher than the P-gp positive group(P < 0.01). 3) The response rate in the patients with skin and lymph node metastasis was higher than the patients with lung and liver metastasis (P < 0.05). 4) The postoperative patients who had received CAF(cyclophosphamide + adriamycin + 5-fluorouracil) or CMF(cyclophosphamide + methotrexate + 5-fluorouracil) regimen adjuvant chemotherapy previously, the response rate of metastatic diseases to chemotherapy had no significant difference (P > 0.05).

Conclusions: P-gp expression may be considered as an index for evaluating multidrug resistance, guiding drug use, and judging prognosis of the patients with metastatic breast carcinoma.