After approval by the Institutional Review Board, the pathology database of the Montefiore Medical Center (NY, USA) was searched to identify ER+ BC cases with: (i) low-risk (<18) or high-risk (>31) ODX RS; (ii) sufficient tissue for both ZNF217 immunohistochemistry (IHC) (Nguyen et al., 2014) and ZNF217 RTQ-PCR (Loudig et al., 2007; Kotorashvili et al., 2012; Vendrell et al., 2012) investigations. The gene discussed is ESR1; the disease is breast cancer.