ESR1 and breast cancer: In addition, the breast cancer risk was increased also in the other subgroups, e.g., ER negative (OR 2.34, 95% CI 0.75–7.35, P = 0.14) and familial breast cancer (OR 2.50, 95% CI 0.83–7.51, P = 0.10) (Table 2), but the results did not reach statistical significance.