ESR1 and cancer: On the contrary, ER positive (HR = 0.67, 95% CI: 0.64–0.71), PR positive (HR = 0.61, 95% CI: 0.58–0.64), HER-2 positivity (HR = 0.56, 95% CI: 0.54–0.59), and breast surgery (HR = 0.33, 95% CI: 0.31–0.34) were associated with significantly reduced risks of cancer-related death (Table 2).