title: Clinical relevance of HER2 overexpression/amplification in patients with small tumor size and node-negative breast cancer.
abstract: OBJECTIVE
  To assess the prognostic role of HER2 overexpression/amplification in patients with node-negative, pT1a-b breast cancers.
  
  
  METHODS
  All patients with HER2-positive breast cancer were identified among a population of 2,130 patients whose diseases were staged as pT1a-b, pN0 and who underwent surgery at the European Institute of Oncology from 1999 to 2006. A matched cohort was selected by using variables of hormone receptor status, age, and year of surgery. We estimated rates of local and distant recurrence, disease-free survival (DFS), and overall survival (OS) in the two groups.
  
  
  RESULTS
  We identified 150 consecutive patients with pT1a-b, pN0, HER2-positive tumors. No patient received adjuvant trastuzumab. The median follow-up was 4.6 years (range, 1.0 to 9.0 years). In the hormone receptor-positive group, 5-year DFS rates were 99% (95% CI, 96% to 100%) for HER2-negative disease and 92% (95% CI, 86% to 99%) for HER2-positive disease. In the hormone receptor-negative group, 5-year DFS rates were 92% (95% CI, 84% to 100%) for HER2-negative disease and 91% (95% CI, 84% to 99%) for HER2-positive disease. Overall, the hazard ratio (HR) associated with HER2 overexpression was 2.4 (95% CI, 0.9 to 6.5; P = .09). After analysis was adjusted for pT1 stage, hormone receptor-positive disease with HER2-positive status was associated with a worse prognosis (HR, 5.1; 95% CI, 1.0 to 25.7). OS in HER2-positive, pT1a-b, pN0 breast cancer was similar irrespective of the hormone receptor status (P = .93).
  
  
  CONCLUSIONS
  Patients with node-negative, HER2 positive, pT1a-b breast cancer have a low risk of recurrence at 5 years of follow-up. In patients with hormone receptor-positive disease and pT1a-b, N0 tumors, HER2 overexpression was associated with a worse DFS.
authors.affiliation: Department of Medicine, Division of Medical Oncology, Istituto Europeo di Oncologia, Milano, Italy. giuseppe.curigliano@ieo.it
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Curigliano
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Viale
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Bagnardi
authors.forename: Luca
authors.initials: L
authors.lastname: Fumagalli
authors.forename: Marzia
authors.initials: M
authors.lastname: Locatelli
authors.forename: Nicole
authors.initials: N
authors.lastname: Rotmensz
authors.forename: Raffaella
authors.initials: R
authors.lastname: Ghisini
authors.forename: Marco
authors.initials: M
authors.lastname: Colleoni
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Munzone
authors.forename: Paolo
authors.initials: P
authors.lastname: Veronesi
authors.forename: Stefano
authors.initials: S
authors.lastname: Zurrida
authors.forename: Franco
authors.initials: F
authors.lastname: Nolè
authors.forename: Aron
authors.initials: A
authors.lastname: Goldhirsch
mesh_terms: D001943:Breast Neoplasms / Q000737:chemistry / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008875:Middle Aged; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis*; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone