The 21-gene recurrence score assay impacts adjuvant therapy recommendations for ER-positive, node-negative and node-positive early breast cancer resulting in a risk-adapted change in chemotherapy use

BACKGROUND: We carried out a prospective clinical study to evaluate the impact of the Recurrence Score (RS) on treatment decisions in early breast cancer (EBC). PATIENTS AND METHODS: A total of 379 eligible women with estrogen receptor positive (ER+), HER2-negative EBC and 0–3 positive lymph nodes were enrolled. Treatment recommendations, patients' decisional conflict, physicians' confidence before and after knowledge of the RS and actual treatment data were recorded. RESULTS: Of the 366 assessable patients 244 were node negative (N0) and 122 node positive (N+). Treatment recommendations changed in 33% of all patients (N0 30%, N+ 39%). In 38% of all patients (N0 39%, N+ 37%) with an initial recommendation for chemoendocrine therapy, the post-RS recommendation changed to endocrine therapy, in 25% (N0 22%, N+ 39%) with an initial recommendation for endocrine therapy only to combined chemoendocrine therapy, respectively. A patients' decisional conflict score improved by 6% (P = 0.028) and physicians' confidence increased in 45% (P < 0.001) of all cases. Overall, 33% (N0 29%, N+ 38%) of fewer patients actually received chemotherapy as compared with patients recommended chemotherapy pre-test. Using the test was cost-saving versus current clinical practice. CONCLUSION: RS-guided chemotherapy decision-making resulted in a substantial modification of adjuvant chemotherapy usage in node-negative and node-positive ER+ EBC.