title: Utility of Oncotype DX Risk Assessment in Patients With Invasive Lobular Carcinoma.
abstract: BACKGROUND
  Oncotype DX (Genomic Health, Redwood City, CA) uses reverse transcriptase polymerase chain reaction analysis to measure tumor gene expression for determining recurrence risk (RR) and guiding chemotherapy decisions for breast cancer patients. Invasive lobular carcinoma (ILC) is a histologic subtype that has not been the focus of prior studies validating Oncotype DX. The study purpose was to develop a model using histologic tumor characteristics to predict uniformly low Oncotype DX Recurrence Scores (RS) in ILC.
  
  
  METHODS
  ILC cases in our pathology database with Oncotype DX testing were identified. Histologic tumor characteristics, immunohistochemical (IHC) of estrogen receptor (ER)/progesterone receptor (PgR) percent, HER2, E-cadherin expression, and Ki-67 levels were obtained for cases. Discriminant analysis was used to test the hypothesis that tumors classified as lower/higher risk based on Oncotype DX RS would differ significantly on a linear combination of variables.
  
  
  RESULTS
  From 2006 - 2014, 158 cases of ILC having Oncotype DX testing were identified; 90 low risk (RS < 18), 66 intermediate risk (RS 18 - 30) and 2 high risk (RS > 30). Discriminant analysis showed that PgR% followed by Ki-67 provided the greatest contribution to discern low versus elevated RS. A subset of 57 cases (∼36%) with predicted probabilities > 86% for either low or high RS yielded 96.5% correct classification, 92.3% sensitivity, and 97.7% specificity.
  
  
  CONCLUSIONS
  Our analytical model may be useful in predicting lower RR in patients with ILC. If validated, this provides a faster and less expensive alternative to Oncotype DX testing in certain patients with ILC.
authors.affiliation: Allina Health System, Virginia Piper Cancer Institute, Minneapolis, MN.
authors.forename: Michaela L
authors.initials: ML
authors.lastname: Tsai
authors.affiliation: Hospital Pathology Associates and Allina Health Laboratories, Minneapolis, MN.
authors.forename: Tamera J
authors.initials: TJ
authors.lastname: Lillemoe
authors.affiliation: Allina Health System, Courage Kenny Research Center, Minneapolis, MN.
authors.forename: Marsha J
authors.initials: MJ
authors.lastname: Finkelstein
authors.affiliation: Allina Health System, Virginia Piper Cancer Institute, Minneapolis, MN.
authors.forename: Joel E
authors.initials: JE
authors.lastname: Money
authors.affiliation: Hospital Pathology Associates and Allina Health Laboratories, Minneapolis, MN.
authors.forename: Barbara
authors.initials: B
authors.lastname: Susnik
authors.affiliation: Hospital Pathology Associates and Allina Health Laboratories, Minneapolis, MN.
authors.forename: Erin
authors.initials: E
authors.lastname: Grimm
authors.affiliation: Hospital Pathology Associates and Allina Health Laboratories, Minneapolis, MN.
authors.forename: Sung-Hae L
authors.initials: SH
authors.lastname: Kang
authors.affiliation: Allina Health System, Virginia Piper Cancer Institute, Minneapolis, MN. Electronic address: Karen.Swenson2@allina.com.
authors.forename: Karen K
authors.initials: KK
authors.lastname: Swenson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology*; D018275:Carcinoma, Lobular / Q000235:genetics / Q000473:pathology*; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods*; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000235:genetics / Q000473:pathology; D011379:Prognosis; D012372:ROC Curve; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor
keywords: Breast carcinoma; Immunohistochemistry; Multigene assay; Predictive factors; Recurrence