title: Chemotherapy benefit for 'ER-positive' breast cancer and contamination of nonluminal subtypes—waiting for TAILORx and RxPONDER.
abstract: BACKGROUND
  Retrospective analyses of NSABP B20 and SWOG 8814 showed a large benefit of chemotherapy in patients with ER-positive tumors and high OncotypeDX Recurrence Score (RS≥31). However, it might be possible that both studies may be contaminated by non-luminal tumors, especially in high-risk RS group.
  
  
  METHODS
  We conducted simulations in order to obtain a better understanding of how the NSABP B20 and SWOG 8814 results would have been if non-luminal breast cancer would have been excluded. Simulations were done separately for the node-negative and node-positive cohorts.
  
  
  CONCLUSIONS
  The results of the simulations suggest that the non-luminal tumors are augmenting the apparent benefit of chemotherapy, but do not appear to be responsible for the entire effect. These simulations could provide information about the potential influence of contamination by unexpected tumor subtypes on the future results of TAILORx and RxPONDER clinical trials.
authors.affiliation: IBCSG Statistical Center, Dana-Farber Cancer Institute and Harvard School of Public Health, Boston, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Translational Genomics Group, Vall D'Hebron Institute of Oncology (VHIO), Barcelona; Department of Medical Oncology, Hospital Clínic, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Prat
authors.affiliation: Clinical Trials and Statistics Unit, The Institute of Cancer Research, Belmont, UK.
authors.forename: M C U
authors.initials: MCU
authors.lastname: Cheang
authors.affiliation: IBCSG Statistical Center, Dana-Farber Cancer Institute and Harvard School of Public Health, Boston, USA. Electronic address: gelber@jimmy.harvard.edu.
authors.forename: R D
authors.initials: RD
authors.lastname: Gelber
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, USA. Electronic address: chuck_perou@med.unc.edu.
authors.forename: C M
authors.initials: CM
authors.lastname: Perou
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology*; D017024:Chemotherapy, Adjuvant; D003198:Computer Simulation; D005260:Female; D006801:Humans; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy; D011960:Receptors, Estrogen / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D011960:Receptors, Estrogen
keywords: ER-positive; Her2-enriched; OncotypeDX Recurrence Score; PAM50; basal-like; luminal A; luminal B