In addition, the histological grade of primary ER-positive/HER2-negative breast tumors has been shown to be an independent predictor of relapse-free survival (hazard ratio = 2.13, 95% confidence interval, 1.79–2.53; P < 0.0001; Rakha et al., 2008; Rakha et al., 2010). The gene discussed is ERBB2; the disease is breast neoplasm.