title: Association of an extracellular matrix gene cluster with breast cancer prognosis and endocrine therapy response.
abstract: OBJECTIVE
  We previously discovered an extracellular matrix (ECM) gene cluster associated with resistance to first-line tamoxifen therapy of patients with metastatic breast cancer. In this study, we determined whether the six individual ECM genes [collagen 1A1 (COL1A1), fibronectin 1 (FN1), lysyl oxidase (LOX), secreted protein acidic cysteine-rich (SPARC), tissue inhibitor of metalloproteinase 3 (TIMP3), and tenascin C (TNC)] were associated with treatment response, prognosis, or both.
  
  
  METHODS
  In 1,286 primary breast tumors, mRNA expression (quantitative real-time PCR) was related to clinicopathologic factors and disease outcome in univariate and multivariate analysis including traditional factors.
  
  
  RESULTS
  TIMP3, FN1, LOX, and SPARC expression levels (continuous variables) were significantly associated with distant metastasis-free survival (MFS) in 680 lymph node-negative untreated patients (P<0.03). Using a calculated linear prognostic score, these patients were evenly divided into five prognostic groups with a significant difference in 10-year MFS of approximately 40% between the two extreme prognostic groups. Furthermore, high TNC expression as continuous variable was associated with (a) shorter MFS in 139 estrogen receptor-positive and lymph node-positive patients who received adjuvant tamoxifen therapy (hazard ratio, 1.53; P=0.001), and (b) no clinical benefit (odds ratio, 0.81; P=0.035) and shorter progression-free survival (hazard ratio, 1.19; P=0.002) in 240 patients in whom recurrence was treated with tamoxifen as first-line monotherapy. These results were also significant in multivariate analyses.
  
  
  CONCLUSIONS
  FN1, LOX, SPARC, and TIMP3 expression levels are associated with the prognosis of patients with breast cancers, whereas TNC is associated with resistance to tamoxifen therapy. Further validation and functional studies are necessary to determine the use of these ECM genes in decisions regarding treatment and whether they can serve as targets for therapy.
authors.affiliation: Department of Medical Oncology, Erasmus MC/Daniel den Hoed Cancer Center, Rotterdam, the Netherlands.
authors.forename: Jozien
authors.initials: J
authors.lastname: Helleman
authors.forename: Maurice P H M
authors.initials: MP
authors.lastname: Jansen
authors.forename: Kirsten
authors.initials: K
authors.lastname: Ruigrok-Ritstier
authors.forename: Iris L
authors.initials: IL
authors.lastname: van Staveren
authors.forename: Maxime P
authors.initials: MP
authors.lastname: Look
authors.forename: Marion E
authors.initials: ME
authors.lastname: Meijer-van Gelder
authors.forename: Anieta M
authors.initials: AM
authors.lastname: Sieuwerts
authors.forename: Jan G M
authors.initials: JG
authors.lastname: Klijn
authors.forename: Stefan
authors.initials: S
authors.lastname: Sleijfer
authors.forename: John A
authors.initials: JA
authors.lastname: Foekens
authors.forename: Els M J J
authors.initials: EM
authors.lastname: Berns