title: Estimating the OncotypeDX score: validation of an inexpensive estimation tool.
abstract: OncotypeDX, a multi-gene expression assay, has been incorporated into clinical practice as a prognostic and predictive tool. However, its use in resource-constrained international healthcare systems is limited. Here we develop and validate a simplified model using clinicopathologic criteria to predict OncotypeDX score.
  
  
  
  Patients with estrogen receptor (ER) and/or progesterone receptor (PR)-positive and HER2-negative invasive ductal carcinoma for whom the OncotypeDX test was successfully performed between 09/2008 and 12/2011 were retrospectively identified. Tumor size, nuclear and histologic grade, lymphovascular invasion, and ER and PR status were extracted from pathology reports. Data were split into a training dataset comprising women tested 09/2008-04/2011, and a validation dataset comprising women tested 04/2011-12/2011. Using the training dataset, linear regression analysis was used to identify factors associated with OncotypeDX score, and to create a simplified risk score and identify risk cutoffs.
  
  
  
  Estrogen and progesterone receptors, tumor size, nuclear and histologic grades, and lymphovascular involvement were independently associated with OncotypeDX. The full model explained 39% of the variation in the test data, and the simplified risk score and cutoffs assigned 57% of patients in the test data to the correct risk category (OncotypeDX score <18, 18-30, >30). 41% of patients were predicted to have OncotypeDX score <18, of these 83, 16, and 2% had true scores of <18, 18-30, and >30, respectively.
  
  
  
  Awaiting an inexpensive test that is prognostic and predictive, our simplified tool allows clinicians to identify a fairly large group of patients (41%) with very low chance of having high-risk disease (2%).
authors.affiliation: Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: Anne A
authors.initials: AA
authors.lastname: Eaton
authors.affiliation: Department of Surgical Oncology, NorthShore University HealthSystem, Evanston, IL, USA.
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Pesce
authors.affiliation: University Hospital Waterford, Waterford, Ireland.
authors.forename: James O
authors.initials: JO
authors.lastname: Murphy
authors.affiliation: Breast Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, 300 East 66th Street, New York, NY, 10065, USA.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Stempel
authors.affiliation: Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: Sujata M
authors.initials: SM
authors.lastname: Patil
authors.affiliation: Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: Edi
authors.initials: E
authors.lastname: Brogi
authors.affiliation: Breast Cancer Medicine Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: Clifford A
authors.initials: CA
authors.lastname: Hudis
authors.affiliation: Breast Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, 300 East 66th Street, New York, NY, 10065, USA. eltamerm@mskcc.org.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: El-Tamer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods* / Q000592:standards; D005820:Genetic Testing / Q000379:methods* / Q000592:standards; D006801:Humans; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics; D011960:Receptors, Estrogen / Q000235:genetics; D011980:Receptors, Progesterone / Q000235:genetics; D015203:Reproducibility of Results; D012307:Risk Factors; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone
keywords: Breast cancer; OncotypeDX; Risk prediction