BACKGROUND: Oncotype DX breast cancer assay (Genomic Health, Redwood City, 
Calif) stratifies patients with early breast cancer according to risk of distant 
recurrence. The authors hypothesized that the test is ordered when 
clinicopathological variables yield equivocal risk estimates. The current study 
also showed how often the test clarifies clinically ambiguous risk status.
METHODS: The authors examined clinical/pathological characteristics and 
calculated risk of recurrence with Adjuvant! for 309 consecutive patients who 
underwent Oncotype DX testing at M. D. Anderson Cancer Center.
RESULTS: Of the patients comprising this study, most had stage I/II (n = 306, 
99%) and grade I/II tumors (n = 236, 76%). The median risk of recurrence by 
Adjuvant! was 16% (IQR 11.2 to 20.4). Oncotype DX stratified 52% (n = 160), 40% 
(n = 122) and 9% (n = 27) of this clinically intermediate risk population into 
low, intermediate, and high risk groups, respectively. Correlation between 
projected risk of recurrence by Adjuvant! (Adjuvant!, online software and 
website) and Oncotype DX was minimal (r = 0.13). Recurrence score (P < .0001), 
but not age or tumor size, was higher in patients who received adjuvant 
chemotherapy. In all 3 grade subsets, recurrence score was higher in those who 
received chemotherapy compared with those who did not (P = .02, P < .0001, and P 
= .0009, respectively). All lobular carcinomas (n = 40) were classified as 
low/intermediate risk.
CONCLUSIONS: Oncotype DX yielded potentially informative risk assignments in 
patients considered indeterminate risk by routine clinical variables. However, 
40% of the time test results reflected intermediate risk, with widely used 
recurrence score thresholds. This proportion increased to 66% using revised 
thresholds implemented by National Cancer Institute's Trial Assigning 
IndividuaLized Options for Treatment (Rx), or TAILORx.