Utility of oncotype DX risk estimates in clinically intermediate risk hormone receptor‐positive, HER2‐normal, grade II, lymph node‐negative breast cancers

Abstract

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. 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. 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. 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.