title: Progesterone receptor loss identifies Luminal B breast cancer subgroups at higher risk of relapse.
abstract: BACKGROUND
  The immunohistochemical (IHC) evaluation of estrogen receptor (ER), progesterone receptor (PgR), Ki-67 and HER2 is considered a surrogate means for identifying the molecular subtypes of breast cancer with different prognosis.
  
  
  METHODS
  We explored patterns of recurrence in 4837 women with breast cancer defined as Luminal B (ER-positive and/or PgR-positive, HER2 positive and/or Ki-67≥14%) by IHC classification. We evaluated four subgroups within the Luminal B subtype according to HER2 expression and PgR status.
  
  
  RESULTS
  Patients within the ER+/PgR+/HER2- subgroup presented a 5-year breast cancer-related survival (BCS) of 97% (95% confidence interval (CI), 96-97) and overall survival (OS) of 95% [95% CI, 95-96], the best survivals of the Luminal B subgroups. In the multivariate analysis, the ER+/PgR-/HER2- subgroup was associated with a reduced BCS (HR 1.71; 95%CI, 1.25-2.35) and OS (HR 1.47; 95%CI, 1.10-1.96) when compared with the ER+/PgR+/HER2- subgroup. Also patients within the ER+/PgR-/HER2+ subgroup had a reduced BCS (HR 1.93; 95%CI, 1.32-2.83) and OS (HR 1.62; 95%CI, 1.14-2.30) when compared with ER+/PgR+/HER2- subgroup. On the other hand, no statistically significant differences were found with regard to BCS and OS among patients with ER+/PgR+/HER2+ and patients with ER+/PgR+/HER2- disease.
  
  
  CONCLUSIONS
  PgR loss identifies Luminal B breast cancer subgroups at higher risk of relapse and death, both with HER-2-positive and HER-2-negative disease.
authors.affiliation: Research Unit in Medical Senology, Department of Medicine, European Institute of Oncology, Milan 20141, Italy. giuseppe.cancello@ieo.it
authors.forename: G
authors.initials: G
authors.lastname: Cancello
authors.forename: P
authors.initials: P
authors.lastname: Maisonneuve
authors.forename: N
authors.initials: N
authors.lastname: Rotmensz
authors.forename: G
authors.initials: G
authors.lastname: Viale
authors.forename: M G
authors.initials: MG
authors.lastname: Mastropasqua
authors.forename: G
authors.initials: G
authors.lastname: Pruneri
authors.forename: E
authors.initials: E
authors.lastname: Montagna
authors.forename: M
authors.initials: M
authors.lastname: Iorfida
authors.forename: M
authors.initials: M
authors.lastname: Mazza
authors.forename: A
authors.initials: A
authors.lastname: Balduzzi
authors.forename: P
authors.initials: P
authors.lastname: Veronesi
authors.forename: A
authors.initials: A
authors.lastname: Luini
authors.forename: M
authors.initials: M
authors.lastname: Intra
authors.forename: A
authors.initials: A
authors.lastname: Goldhirsch
authors.forename: M
authors.initials: M
authors.lastname: Colleoni
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000378:metabolism* / Q000401:mortality; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism* / Q000401:mortality; D018275:Carcinoma, Lobular / Q000378:metabolism* / Q000401:mortality; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local / Q000378:metabolism*; D016016:Proportional Hazards Models; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism*
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human