title: Relevance of progesterone receptor immunohistochemical staining to Oncotype DX recurrence score.
abstract: OBJECTIVE
  Progesterone-receptor negativity (PR-) is predictive of adverse outcomes in estrogen receptor-positive (ER+) breast cancer. The Oncotype DX assay provides risk stratification for hormone receptor-positive (HR+) invasive breast cancer; however, the association of PR status and Oncotype DX recurrence scores (RSs) is less clear.
  
  
  METHODS
  We designed an analysis to determine whether a significant difference exists in the RS for ER+/PR- tumors when compared with ER+/PR+ breast cancer. Three hundred and fifty patients with HR+ invasive breast cancer who underwent Oncotype DX testing at our institution from December 2006 to October 2013 were included. We also examined the concordance in the HR status reported by immunohistochemical (IHC) and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses. The data were analyzed by analysis of variance, F test, t test, and chi-square tests. Multivariate linear regression was used to determine significant predictors of Oncotype DX RS.
  
  
  RESULTS
  A total of 301 patients had ER+/PR+ tumors and 47 patients had ER+/PR- tumors by IHC. PR- tumors had a significantly higher RS than PR+ tumors (24.7±8.53 vs. 17.3±7.38; p<.001), predicting a greater 10-year risk of distant recurrence. Multivariate linear regression showed PR status and tumor grade to be significant predictors of Oncotype DX RS (p<.0001). A total of 284 patients had HR status reported by Oncotype DX assay. Concordance between IHC and RT-PCR was 99.3% for ER and 88.7% for PR.
  
  
  CONCLUSIONS
  Our study shows that ER+/PR- breast cancer tumors are associated with a significantly higher Oncotype DX scores; this interprets into a higher risk of recurrence. Our data also show that the concordance between IHC and RT-PCR was 99.3% for ER and lower at 88.7% for PR.
authors.affiliation: Division of Hematology and Oncology, Medical College of Wisconsin, WI, USA. Electronic address: lchaudhary@mcw.edu.
authors.forename: Lubna N
authors.initials: LN
authors.lastname: Chaudhary
authors.affiliation: Department of Internal Medicine, Medical College of Wisconsin, WI, USA.
authors.forename: Zeeshan
authors.initials: Z
authors.lastname: Jawa
authors.affiliation: Division of Biostatistics, Medical College of Wisconsin, WI, USA.
authors.forename: Aniko
authors.initials: A
authors.lastname: Szabo
authors.affiliation: Division of Biostatistics, Medical College of Wisconsin, WI, USA.
authors.forename: Alexis
authors.initials: A
authors.lastname: Visotcky
authors.affiliation: Division of Hematology and Oncology, Medical College of Wisconsin, WI, USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Chitambar
mesh_terms: D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D016014:Linear Models; D008875:Middle Aged; D015999:Multivariate Analysis; D060787:Neoplasm Grading; D009364:Neoplasm Recurrence, Local / Q000378:metabolism* / Q000473:pathology*; D060888:Real-Time Polymerase Chain Reaction; D011980:Receptors, Progesterone / Q000378:metabolism*; D013194:Staining and Labeling
chemical_list: D011980:Receptors, Progesterone
keywords: Breast cancer; Estrogen receptor; Genomic profiling; Progesterone receptor