In addition, univariate analysis of breast cancer-specific survival in all cases, including stage IV patients (n = 140), showed lymph node metastasis (p = 0.0006), pT (p = 0.0012), KLK12 status (p = 0.0049) and Histological grade (p = 0.041) were significant prognostic factors and following multivariate analysis revealed that lymph node metastasis (p = 0.032) and KLK12 status (p = 0.016) were independent favorable prognostic factors (Supplementary Table S1). Here, KLK12 is linked to breast cancer.