title: High estrogen receptor expression and low Ki67 expression are associated with improved time to progression during first-line endocrine therapy with aromatase inhibitors in breast cancer.
abstract: BACKGROUND
  Aromatase inhibitors have played a central role in endocrine therapy for estrogen receptor (ER)-positive breast cancer in postmenopausal women. However, many breast cancer patients with tumors expressing ER are unresponsive to aromatase inhibitors, and all patients with advanced disease eventually develop resistance to the therapy.
  
  
  METHODS
  Twenty-one postmenopausal women with Stage II to IV breast cancer were treated with aromatase inhibitors as first-line endocrine therapy without surgery. Expression levels of ER, progesterone receptor, HER2 and Ki67 were examined by immunohistochemistry, and correlations between response and duration of the therapy and these levels were analyzed.
  
  
  RESULTS
  Patients whose tumors contained two thirds or more ER-positive cells effectively responded to aromatase inhibitors (P = 0.006) and displayed longer time to progression during first-line endocrine therapy (P = 0.003) and longer time to endocrine therapy failure (P = 0.02). Patients whose tumors showed less than 15% Ki67 labeling index also displayed longer time to progression (P = 0.003).
  
  
  CONCLUSIONS
  High ER expression and low Ki67 expression were associated with improved time to progression with aromatase inhibitors as first-line endocrine therapy. Our findings will be helpful when endocrine therapy is planned in either early stage or advanced breast cancer.
authors: Oncology, Immunology and Surgery, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan.
authors: Yumi
authors: Y
authors: Endo
authors: Tatsuya
authors: T
authors: Toyama
authors: Satoru
authors: S
authors: Takahashi
authors: Hiroshi
authors: H
authors: Sugiura
authors: Nobuyasu
authors: N
authors: Yoshimoto
authors: Mai
authors: M
authors: Iwasa
authors: Shunzo
authors: S
authors: Kobayashi
authors: Yoshitaka
authors: Y
authors: Fujii
authors: Hiroko
authors: H
authors: Yamashita
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D047072:Aromatase Inhibitors / Q000627:therapeutic use*; D054316:Biomarkers, Pharmacological / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020249:Hormone Replacement Therapy; D006801:Humans; D019394:Ki-67 Antigen / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D009367:Neoplasm Staging; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy*; D017698:Postmenopause; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011960:Receptors, Estrogen / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism
chemical_list: D047072:Aromatase Inhibitors; D054316:Biomarkers, Pharmacological; D019394:Ki-67 Antigen; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human