title: A simple and reproducible prognostic index in luminal ER-positive breast cancers.
abstract: BACKGROUND
  The group of estrogen receptor (ER)-positive breast cancers (both luminal-A and -B) behaves differently from the ER-negative group. At least in early follow-up, ER expression influences positively patients' prognosis. This low aggressive biology flattens out the differences of clinical management. Thus we aimed to produce a prognostic index specific for ER-positive (ERPI) cancers that could be of aid for clinical decision.
  
  
  METHODS
  The test set comprised 495 consecutive ER-positive breast cancers. Tumor size, number of metastatic lymph nodes and androgen receptor expression were the only independent variables related to disease-specific survival. These variables were used to create the ERPI, which was applied to the entire test set and to selected subpopulations (grade 2 (G2)-tumors, luminal-A and -B breast cancers). A series of 581 ER-positive breast cancers, collected from another hospital, was used to validate ERPI.
  
  
  RESULTS
  In the test population, 96.9% of patients classified as ERPI-good showed a good prognosis compared with 79.6% classified as ERPI-poor (P < 0.001). ERPI effectively discriminated outcome in luminal-A and luminal-B and in G2-tumors. In the validation series, the ERPI maintained its value.
  
  
  CONCLUSIONS
  ERPI is a practical tool in refining the prediction of outcome of patients with ER-positive breast cancer.
authors.affiliation: Department of Medical Sciences, University of Turin, Turin, Italy. isabella.castellano@unito.it
authors.forename: I
authors.initials: I
authors.lastname: Castellano
authors.forename: L
authors.initials: L
authors.lastname: Chiusa
authors.forename: A M
authors.initials: AM
authors.lastname: Vandone
authors.forename: S
authors.initials: S
authors.lastname: Beatrice
authors.forename: M
authors.initials: M
authors.lastname: Goia
authors.forename: M
authors.initials: M
authors.lastname: Donadio
authors.forename: R
authors.initials: R
authors.lastname: Arisio
authors.forename: F
authors.initials: F
authors.lastname: Muscarà
authors.forename: A
authors.initials: A
authors.lastname: Durando
authors.forename: G
authors.initials: G
authors.lastname: Viale
authors.forename: P
authors.initials: P
authors.lastname: Cassoni
authors.forename: A
authors.initials: A
authors.lastname: Sapino
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy / Q000401:mortality*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis / Q000473:pathology*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011944:Receptors, Androgen / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; D011944:Receptors, Androgen; D011960:Receptors, Estrogen; C410798:AR protein, human
keywords: AR expression; ER expression; breast cancer; lymph nodal status; prognostic index; tumor size