ESR1 and breast carcinoma: Meta-analysis across 9 independent breast cancer data sets revealed that like signalling entropy, the SE score is prognostic across both ER positive and ER negative samples (ER positive: c-index = 0.63, 95% CI = (0.59, 0.67), p = 4.6e − 15, ER negative: c-index = 0.62, 95% CI = (0.58, 0.66), p = 8.1e − 8, Fig. 4A).