title: Agreement in risk prediction between the 21-gene recurrence score assay (Oncotype DX®) and the PAM50 breast cancer intrinsic Classifier™ in early-stage estrogen receptor-positive breast cancer.
abstract: OBJECTIVE
  To compare risk assignment by PAM50 Breast Cancer Intrinsic Classifier™ and Oncotype DX_Recurrence Score (RS) in the same population.
  
  
  METHODS
  RNA was extracted from 151 estrogen receptor (ER)+ stage I-II breast cancers and gene expression profiled using PAM50 "intrinsic" subtyping test.
  
  
  RESULTS
  One hundred eight cases had complete molecular information; 103 (95%) were classified as luminal A (n = 76) or luminal B (n = 27). Ninety-two percent (n = 98) had a low (n = 59) or intermediate (n = 39) RS. Among luminal A cancers, 70% had low (n = 53) and the remainder (n = 23) had an intermediate RS. Among luminal B cancers, nine were high (33%) and 13 were intermediate (48%) by the RS. Almost all cancers with a high RS were classified as luminal B (90%, n = 9). One high RS cancer was identified as basal-like and had low ER/ESR1 and low human epidermal growth factor receptor 2 (HER2) expression by quantitative polymerase chain reaction in both assays. The majority of low RS cases were luminal A (83%, n = 53). Importantly, half of the intermediate RS cancers were re-categorized as low risk luminal A subtype by PAM50.
  
  
  CONCLUSIONS
  There is good agreement between the two assays for high (i.e., luminal B or RS > 31) and low (i.e., luminal B or RS < 18) prognostic risk assignment but PAM50 assigns more patients to the low risk category. About half of the intermediate RS group was reclassified as luminal A by PAM50.
authors.affiliation: Department of Medical Oncology, Mater Misericordiae University Hospital, Dublin, Ireland.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Kelly
authors.forename: Philip S
authors.initials: PS
authors.lastname: Bernard
authors.forename: Savitri
authors.initials: S
authors.lastname: Krishnamurthy
authors.forename: Bailiang
authors.initials: B
authors.lastname: Wang
authors.forename: Mark T W
authors.initials: MT
authors.lastname: Ebbert
authors.forename: Roy R L
authors.initials: RR
authors.lastname: Bastien
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Boucher
authors.forename: Elliana
authors.initials: E
authors.lastname: Young
authors.forename: Takayuki
authors.initials: T
authors.lastname: Iwamoto
authors.forename: Lajos
authors.initials: L
authors.lastname: Pusztai
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000145:classification / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D015331:Cohort Studies; D055088:Early Detection of Cancer / Q000379:methods; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D011237:Predictive Value of Tests; D011960:Receptors, Estrogen / Q000378:metabolism*; D018570:Risk Assessment; D012307:Risk Factors
chemical_list: D014408:Biomarkers, Tumor; D011960:Receptors, Estrogen