title: Variation in hormone receptor and HER-2 status between primary and metastatic breast cancer: review of the literature.
abstract: BACKGROUND
  Hormone and human epidermal growth factor receptor 2 (HER-2) receptors are two important pharmaceutical targets that affect the survival of patients with metastatic breast cancer. Discordance of hormone and HER-2 receptors were reported in a series of studies. Receptor status was reported to change in both directions, yet alteration occurs mostly in the loss of positivity for both receptors. We do not know both the exact mechanism of this process or the contribution rate of technical mistakes; a number of mechanisms might be responsible. Factors suggested include: tumor heterogeneity, clonal selection of tumor cell subpopulations, genetic instability of tumor cells, local or systemic treatments, the time interval between primary tumor and metastasis, receptor status determination techniques, and the site of metastasis.
  
  
  METHODS
  Studies of estrogen, progesterone and HER-2 receptor discordance between primary and metastasis of breast cancer are summarized. Laboratory evaluation of estrogen, progesterone and HER-2 receptors, and possible causes of receptor discordance, are summarized. Literature data are reviewed; the major shortcoming of these studies is that they are mostly retrospective.
  
  
  RESULTS
  The reader will read a concise literature review about the studies on estrogen, progesterone and HER-2 receptor discordances between primary and metastasis of breast cancer.
  
  
  CONCLUSIONS
  We do not know whether the changes in receptor expression account for a true biological phenomenon or may result from inconsistent measurement. However, in light of current data, for the treatment plans that target the receptors, biopsy specimen from the metastatis of breast cancer must also be evaulated for alterations in the receptor status.
authors.affiliation: Hacettepe University Institute of Oncology, Ankara, Turkey.
authors.forename: Cagatay
authors.initials: C
authors.lastname: Arslan
authors.forename: Ebru
authors.initials: E
authors.lastname: Sari
authors.forename: Sercan
authors.initials: S
authors.lastname: Aksoy
authors.forename: Kadri
authors.initials: K
authors.lastname: Altundag
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009362:Neoplasm Metastasis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism*; D013534:Survival
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone