title: Reduced occurrence of mdr-1 amplification in stage-IV breast-cancer patients treated with tamoxifen compared with other endocrine treatments.
abstract: Amplification of mdr-1 occurs in breast cancer patients receiving endocrine treatment. We have compared a group of patients receiving tamoxifen and a group receiving second-line endocrine treatment after failure of tamoxifen treatment. Chronological tumor samples were obtained by fine-needle biopsies from the same tumor lesion of each patient and PCR was used to detect the appearance of gene amplification. Three of 20 patients receiving tamoxifen developed amplified mdr-1 whereas 7 of 17 patients receiving second-line endocrine treatment developed mdr-1 amplification.
authors.affiliation: Radiumhemmet, Karolinska Hospital, Stockholm, Sweden.
authors.forename: U
authors.initials: U
authors.lastname: Lönn
authors.forename: S
authors.initials: S
authors.lastname: Lönn
authors.forename: B
authors.initials: B
authors.lastname: Stenkvist
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000368:Aged; D000369:Aged, 80 and over; D000616:Aminoglutethimide / Q000008:administration & dosage; D001707:Biopsy, Needle; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics*; D004273:DNA, Neoplasm / Q000235:genetics; D005784:Gene Amplification; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics*; D008875:Middle Aged; D011374:Progesterone / Q000008:administration & dosage; D013629:Tamoxifen / Q000627:therapeutic use*; D013739:Testosterone / Q000008:administration & dosage
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004273:DNA, Neoplasm; D008562:Membrane Glycoproteins; D013629:Tamoxifen; D000616:Aminoglutethimide; D013739:Testosterone; D011374:Progesterone