Impact of Oncotype DX on treatment decisions in ER-positive, node-negative breast cancer with histologic correlation.

Oncotype DX, a gene-expression profiling assay, provides stratification of patients with estrogen-receptor positive, lymph-node-negative early breast cancer into risk groups based on recurrence score, which are associated with distant recurrence and response to chemotherapy. This study aims to determine whether Oncotype DX influences clinicians' treatment decisions, and whether assay results correlate with histologic assessment. Fifty patients with estrogen-receptor positive, node-negative early breast cancer analyzed by Oncotype DX and operated on by two breast surgeons were included. To assess effect on treatment decisions, clinical vignettes were created by retrospective chart review. Physicians were then presented with the clinical vignettes and instructed to make a treatment decisions (i.e., hormone therapy alone versus hormone therapy combined with chemotherapy) both before and after knowledge of the recurrence score. To assess correlation with histologic assessment, a prospective, blinded review of tumor slides was performed by two pathologists. Based on this review, tumors were placed into low, intermediate and high risk groups for comparison with Oncotype DX assay results. Treatment decisions were changed based on Oncotype DX results in 36 and 18% of cases by breast surgeons and medical oncologists, respectively. All tumors categorized as high risk by Oncotype DX were categorized as high risk based on histologic assessment, and 96% of cases categorized as low risk by recurrence score were categorized as low or intermediate risk by histologic assessment. Oncotype DX significantly influences management of estrogen-receptor positive, lymph-node-negative early breast cancer. Further studies are needed to assess association of histologic categorization to assay results.