title: Clinical outcome of adjuvant endocrine treatment according to Her-2/neu status in breast cancer.
abstract: OBJECTIVE
  An association between over-expression of proto-oncogene Her-2/neu and resistance to tamoxifen in estrogen receptor (ER) positive, primary and metastatic breast cancer has been suggested. HR+/Her-2/neu+ patients have a poor response to endocrine therapy, making this group a matter of debate. The present study was carried out to examine whether Her-2/neu expression in breast cancer patients predicted tamoxifen effectiveness.
  
  
  METHODS
  An enzyme-linked immunosorbent assay (ELISA) specific for the extracellular domain of the Her-2/neu oncoprotein product was used to detect serum Her-2/neu levels in 207 patients with histological confirmed breast cancer. Tissue Her-2 /neu expression was studied in 100 breast cancer patients by immunohistochemistry (IHC) and compared with serum Her-2/neu levels by ELISA.
  
  
  RESULTS
  Among 207 histologically confirmed breast cancer patients, 53 were serum Her-2/neu positive. Patients who were treated with surgery, chemotherapy, and radiotherapy showed significantly (P<0.05) reduced serum Her-2/neu levels, showing good response to treatment. Patients who were treated with tamoxifen in addition to the above regimen did not show any significant reduction in serum Her-2/neu levels showing resistance to treatment.
  
  
  CONCLUSIONS
  The present findings study support the hypothesis that Her-2/neu overexpression contributes to tamoxifen resistance. Trastuzumab or other growth factor inhibitors should be used in combination with tamoxifen, since monotherapy is not likely to be optimal in HR+/Her-2/neu+ tumours.
authors.affiliation: Department of Biochemistry, Kidwai Memorial Institute of Oncology, Bangalore, India.
authors.forename: Rani
authors.initials: R
authors.lastname: James
authors.forename: K
authors.initials: K
authors.lastname: Thriveni
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Krishnamoorthy
authors.forename: Vijayalaxmi
authors.initials: V
authors.lastname: Deshmane
authors.forename: P P
authors.initials: PP
authors.lastname: Bapsy
authors.forename: Girija
authors.initials: G
authors.lastname: Ramaswamy
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology / Q000628:therapy*; D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D019008:Drug Resistance, Neoplasm; D004965:Estrogen Antagonists / Q000627:therapeutic use*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000097:blood / Q000235:genetics*; D013629:Tamoxifen / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D004965:Estrogen Antagonists; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases; D013629:Tamoxifen; C000715470:MAS1 protein, human