Oncotype DX is an RT-PCR assay used to predict which patients with ER-positive 
node-negative (NN) disease will benefit from chemotherapy. Each patient is 
stratified into a risk category based on a recurrence score (RS) and the TAILORx 
trial is determining the benefit of chemotherapy for patients with mid-range 
RSs. We tested if Oncotype DX and TAILORx risk categories could be predicted by 
standard pathological features and protein markers corresponding to 10 genes in 
the assay (ER, PR, Ki67, HER2, BCL2, CD68, Aurora A kinase, survivin, cyclin B1 
and BAG1) on 52 patients who enrolled on TAILORx. Immunohistochemistry for the 
protein markers was performed on whole tissue sections. Classification and 
regression tree (CART) analysis correctly classified 69% of cases into Oncotype 
DX risk categories based on the expression of PR, survivin and nuclear 
pleomorphism. All tumours with PR staining (Allred score ≥ 2) and marked nuclear 
pleomorphism were in the high-risk category. No case with PR <2, low survivin (≤ 
15.5%) and nuclear pleomorphism <3 was high-risk. Similarly, 77% of cases were 
correctly classified into TAILORx categories based on nuclear pleomorphism, 
survivin, BAG1 and cyclin B1. Ki67 was the only variable that predicted the 
absolute RS with a cut-off for positivity of 15% (p = 0.003). In conclusion, 
CART revealed key predictors including proliferation markers, PR and nuclear 
pleomorphism that correctly classified over two thirds of ER-positive NN cancers 
into Oncotype DX and TAILORx risk categories. These variables could be used as 
an alternative to the RT-PCR assay to reduce the number of patients requiring 
Oncotype DX testing.