ESR1 and neoplasm: As is shown in Table 5, low expression of Cytc was associated with higher histological grade (χ2 = 4.278, P = 0.041), ER status (χ2 = 4.609, P = 0.037), PR status (χ2 = 5.424, P = 0.025), and recurrence (χ2 = 8.629, P = 0.004), but not age (χ2 = 0.106, P = 0.763), TNM stage (χ2 = 0.018, P = 0.895), lymph node metastasis (χ2 = 0.003, P = 0.953), HER2 gene amplification (χ2 = 0.36, P = 0.591), or menopause (χ2 = 0.751, P = 0.455) in tumor samples.