In a study from Israel of patients with 1–3 positive lymph nodes, adjuvant chemotherapy was delivered in 70.1% of the 669 control patients, compared to 24.5% in the 282 patients who had RS testing.30 The data from our study analyzing the NCDB similarly demonstrated less chemotherapy recommendation in those who had RS testing (50.4%) compared to those without RS testing (81.0%) in node-positive, ER+/HER2− breast cancer. Here, ESR1 is linked to breast cancer.