ESR1 and neoplasm: The 11-gene proliferation score was also found to be a predictor of recurrence-free survival with an estimated hazard ratio of 1.65 (p-value = 0.03, 95% CI: 1.05; 2.61) for patients in the high-risk group, independently of patients’ age, tumour size, lymph node status, ER status, HER2 status or grade (Fig. 7B).