ERBB4 and breast cancer: However, we failed to detect a significant association between positive nuclear expression of HER4 and the prognosis of breast cancer with regard to both OS (OS: HR = 3.73, CI: 0.39–35.95, P = 0.25, random effects; P = 0.004, I2 = 88.1%; Figure 4C) and RFS (RFS: HR = 0.80, CI: 0.13–4.81, P = 0.80, random effects; P < 0.001, I2 = 89.1%; Figure 4B).