The Oncotype DX Recurrence Score (RS) is a validated genomic predictor of outcome and response to
adjuvant chemotherapy in ER-positive
breast cancer. Adjuvant! was developed using SEER registry data and results from the Early
Breast Cancer Clinical Trialists' overview analyses to estimate outcome and benefit from adjuvant hormonal
therapy and
chemotherapy. In this report we compare the prognostic and predictive utility of these two tools in node-negative, ER-positive
breast cancer. RS and Adjuvant! results were available from 668
tamoxifen-treated NSABP
B-14 patients, 227
tamoxifen-treated NSABP B-20 patients, and 424
chemotherapy plus
tamoxifen-treated B-20 patients. Adjuvant! results were also available from 1952 B-20 patients. The primary endpoint was distant recurrence-free interval (DRFI). Cox proportional hazards models were used to compare the prognostic and predictive utility of RS and Adjuvant!. Both RS (P < 0.001) and Adjuvant! (P = 0.002) provided strong independent prognostic information in
tamoxifen-treated patients. Combining RS and individual clinicopathologic characteristics provided greater prognostic discrimination than combining RS and the composite Adjuvant!. In the B-20 cohort with RS results (n = 651), RS was significantly predictive of
chemotherapy benefit (interaction P = 0.031 for DRFI, P = 0.011 for overall survival [OS], P = 0.082 for disease-free survival [DFS]), but Adjuvant! was not (interaction P = 0.99, P = 0.311, and P = 0.357, respectively). However, in the larger B-20 sub-cohort (n = 1952), Adjuvant! was significantly predictive of
chemotherapy benefit for OS (interaction P = 0.009) but not for DRFI (P = 0.219) or DFS (P = 0.099). Prognostic estimates can be optimized by combining RS and clinicopathologic information instead of simply combining RS and Adjuvant!. RS should be used for estimating relative
chemotherapy benefit.