Breast medical oncologists' use of standard prognostic factors to predict a 21-gene recurrence score

Background: Half of all breast cancers are early stage, lymph node negative, and hormone receptor positive. A 21-gene (Oncotype DX®; Genomic Health, Inc., Redwood City, CA) recurrence score (RS) is prognostic for recurrence and predictive of chemotherapy benefit. We explored the ability of oncologists to predict the RS using standard prognostic criteria.

Methods: Standard demographic and tumor prognostic criteria were obtained from patients with an available RS. Two academic pathologists provided tumor grade, histologic type, and hormone receptor status. Six academic oncologists predicted the RS category (low, intermediate, or high) and provided a recommendation for therapy. The oncologists were then given the actual RS and provided recommendations for therapy. Analysis for agreement was performed.

Results: Thirty-one cases, including nine additional cases with variant pathology reads, were presented. There was substantial agreement in oncologists' ability to discriminate between true low or true intermediate and true high (κ = 0.75; p < .0001). Predictions between low and intermediate were not consistent. The most common discrepancies were predictions of a low RS risk when cases were true intermediate and predictions of an intermediate RS risk when cases were true low. The actual RS resulted in a change in the treatment recommendations in 19% of cases. Of the 186 scenarios and six oncologists in aggregate, five fewer chemotherapy recommendations resulted with the actual RS.

Conclusions: Oncologists are able to differentiate between a low or intermediate RS and a high RS using standard prognostic criteria. However, provision of the actual RS changed the treatment recommendations in nearly 20% of cases, suggesting that the RS may reduce chemotherapy use. This effect was observed in particular in intermediate-risk cases. Prospective clinical trials are necessary to determine whether decisions based on the RS change outcomes.