By contrast, in ER+ breast cancer, the Oncotype Dx (Exact Sciences Corp) multigene assay is widely used to estimate the prognosis and guide the adjuvant treatment decisions.14 Intriguingly, because 5 genes of the ER module have lower recurrence scores (RSs) according to the algorithm,15 the RS from the assay becomes lower in endocrine-sensitive tumors, which might be affected by the estradiol levels. Here, ESR1 is linked to breast cancer.