title: Effect of 21-Gene RT-PCR Assay on Adjuvant Therapy and Outcomes in Patients With Stage I Breast Cancer.
abstract: BACKGROUND
  Recurrence score (RS) derived from a 21-gene reverse transcriptase-polymerase chain reaction assay is used to stratify patients with early-stage estrogen receptor-positive, HER2-normal breast cancer into 3 groups on the basis of 10-year distant metastasis risk: low, intermediate, and high. Published data are limited regarding the effect of RS on choice of adjuvant therapy for T1 breast cancer. We investigated the relationship between RS and choice of adjuvant therapy, prognosis, and benefit of chemotherapy (CT) in stage I breast cancer.
  
  
  METHODS
  We reviewed the records of 1030 patients with estrogen receptor-positive, HER2-normal stage I breast cancer and RS available. RSs were correlated with clinicopathologic characteristics, treatment, and outcome.
  
  
  RESULTS
  Patients with pathologic (p)T1a, pT1b, and pT1c disease did not differ in distribution of low, intermediate, and high RS (P = .673). Overall, fewer than 10% of patients had a high RS. Histologic grade 1, nuclear grade 1, and low Ki-67 expression had only 1%, 0%, and 6% of high RSs, respectively. Among patients with intermediate RSs, 41% with pT1b and 46% with pT1c disease received CT. Among patients with intermediate RSs, for pT1b disease, distant disease-free survival (DDFS) did not differ between hormonal therapy (HT) alone and CT with HT (P = .752); for pT1c, DDFS was superior for CT with HT (P = .020). Histologic grade was the only independent prognostic factor of DDFS (P = .0007, 1 vs. 3; P = .035, 2 vs. 3); RS did not predict DDFS (P = .083, high vs. low; P = .066, intermediate vs. low).
  
  
  CONCLUSIONS
  The added value of RS to known prognostic factors appears limited to patients with pT1b breast cancer. However, this study lacked long-term follow-up.
authors.affiliation: Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX; Department of Medical Oncology, Eugène Marquis Cancer Center, Rennes, France.
authors.forename: Fanny
authors.initials: F
authors.lastname: Le Du
authors.affiliation: Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX; Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Gonzalez-Angulo
authors.affiliation: Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Minjeong
authors.initials: M
authors.lastname: Park
authors.affiliation: Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Diane D
authors.initials: DD
authors.lastname: Liu
authors.affiliation: Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Gabriel N
authors.initials: GN
authors.lastname: Hortobagyi
authors.affiliation: Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX. Electronic address: nueno@mdanderson.org.
authors.forename: Naoto T
authors.initials: NT
authors.lastname: Ueno
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000145:classification* / Q000188:drug therapy / Q000235:genetics*; D017024:Chemotherapy, Adjuvant; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000235:genetics*; D009367:Neoplasm Staging; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012306:Risk; D016896:Treatment Outcome
keywords: Breast neoplasms; Chemotherapy; Disease-free survival; Estrogen; Gene expression profiling; Receptors; Tumor markers