[Clinical significance of P-glycoprotein expression in breast cancer].
OBJECTIVE
To study the clinical significance of P-glycoprotein (P-gp) in breast cancer.


METHODS
Expression of P-gp in 60 cases of breast cancer was examined by immunohistochemistry. P-gp expression and response to chemotherapy were comparatively investigated in 19 patients with metastatic breast cancer.


RESULTS
The P-gp was positive in 48.3% of the 60 cases of breast cancer. P-gp expression was not related to patients' age, menstruation status, number of axillary lymph nodes involved, clinical stage, histological type, and hormonal receptor status(P > 0.05). The frequency of metastasis (62.1%) and mortality (51.7%) were higher in P-gp positive cases than those in negative cases (16.1% vs 12.9%, P < 0.005). The 5-year survival rate of P-gp positive cases (48.3%) was significantly lower than that of negative cases (87.1%) (P < 0.05). In patients received adjuvant chemotherapy distant metastasis occurred more frequently in P-gp positive cases (94.7%) than in P-gp negative cases (57.1%) (P = 0.0468). More P-gp negative patients (7/9) than positive patients (1/10) were responsive to chemotherapy (P = 0.0055).


CONCLUSIONS
Immunohistochemical examination of P-gp expression is useful in predicting response to chemotherapy and prognosis in breast cancer patients. P-gp positivity is associated with poor prognosis.
Department of Medical Oncology, First Clinical Medical College, Xi'an Medical University.
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D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis*; D000230:Adenocarcinoma / Q000737:chemistry* / Q000188:drug therapy / Q000556:secondary; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000737:chemistry* / Q000188:drug therapy / Q000556:secondary; D018270:Carcinoma, Ductal, Breast / Q000737:chemistry / Q000188:drug therapy / Q000556:secondary; D017024:Chemotherapy, Adjuvant; D005260:Female; D006801:Humans; D008875:Middle Aged; D011379:Prognosis; D015996:Survival Rate
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1