Comparison of the intermediate risk 21-gene recurrence score (RS) with the 70-gene signature (GS) as a continuous variable, Magee equations, and Adjuvant! Online (AOL).

Abstract

47 Background: Multigene assays and risk-prediction models are used to provide prognostic information in the management of patients with estrogen receptor positive (ER+) lymph node negative (LN-) breast cancer (BC). Some have predictive utility in determining the value of chemotherapy added to endocrine therapy. We previously reported a mix of high and low risk 70-GS within the intermediate risk 21-gene RS. The Magee equations provide an estimate of the 21-gene RS using standard pathological findings. AOL provides a 10-year risk of BC recurrence or death. The objective of this study is to evaluate correlations between the 70-GS as a nondichotomous continuous variable, the Magee equations, and AOL within patients (pts) with 21-gene intermediate RS. Methods: The 70-GS as a continuous variable (highest risk of -1 to lowest risk of +1) was obtained on all consecutive ER+LN- BC cases with an intermediate 21-gene RS at Loyola U Med Ctr from 1/2005 to 9/2012. AOL recurrence risk and the Magee equations were calculated from clinical-pathologic findings. Pearson pairwise correlations among all four recurrence measures were generated. Results: Results of the 70-GS as a continuous variable and the 21-gene RS were available in 89 cases. A higher risk 70-GS correlates with a higher 21-gene RS (r = -0.31; p = 0.003). A higher risk of recurrence as estimated by AOL is associated with a higher 21-gene RS (r = 0.22; p = 0.036), higher Magee equation 1 (r = 0.36; p = 0.001) and 2 (r = 0.32; p = 0.004), and a higher risk 70-GS (r = -0.40; p < 0.001). Magee equations 1 and 2 are statistically correlated to the 21-gene RS (r = 0.24; p = 0.028 and r = 0.23; p = 0.036 respectively), but not to the 70-GS (p = 0.064 and p = 0.057 respectively). Magee equation 3 is not statistically correlated with 70-GS, 21-gene RS or AOL. Conclusions: There is a continuum of highest to lowest risk 70-GS among LN- ER+ BC within intermediate risk RS. The prospective PROMIS study will assess if the 70-GS adds clinical utility regarding adjuvant therapy choice for these pts.