title: P-glycoprotein immunostaining correlates with ER and with high Ki67 expression but fails to predict anthracycline resistance in patients with advanced breast cancer.
abstract: In an attempt to further define the clinical utility of p-glycoprotein immunostaining in breast cancer, we examined 101 specimens from patients with advanced breast cancer. There was a significant correlation between estrogen receptor status and p-glycoprotein expression but only for low levels of p-glycoprotein. Premenopausal status appeared to correlate with increased p-glycoprotein expression, but this probably reflects patient selection as premenopausal patients had higher prior exposure to anthracyclines and were more likely to have received chemotherapy as initial treatment. P-glycoprotein expression was highly significantly correlated with expression of the proliferation related antigen Ki67, suggesting that p-glycoprotein expression may well be cell cycle dependent, with overexpression occurring in rapidly cycling cells. These findings may explain reported findings of modulation of p-glycoprotein expression by agents such as anti-oestrogens. P-glycoprotein positive staining did not, however, predict chemotherapy treatment failure or survival duration.
authors.affiliation: Department of Medicine, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: L
authors.initials: L
authors.lastname: Seymour
authors.forename: W R
authors.initials: WR
authors.lastname: Bezwoda
authors.forename: R D
authors.initials: RD
authors.lastname: Dansey
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis*; D000328:Adult; D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use*; D000951:Antigens, Neoplasm / Q000032:analysis*; D001943:Breast Neoplasms / Q000737:chemistry* / Q000188:drug therapy / Q000276:immunology / Q000401:mortality; D018567:Breast Neoplasms, Male / Q000737:chemistry; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D019394:Ki-67 Antigen; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis*; D009687:Nuclear Proteins / Q000032:analysis*; D011379:Prognosis; D011960:Receptors, Estrogen / Q000032:analysis*; D015996:Survival Rate; D016896:Treatment Outcome
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D000951:Antigens, Neoplasm; D019394:Ki-67 Antigen; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011960:Receptors, Estrogen