After multivariate analysis, age, histological grade, lymph node metastasis, tumor size, triple-negative breast cancer, and periostin expression were related to post-operative distant metastasis (P = 0.01, 0.001, 0.001, 0.035, 0.001, and 0.001, respectively) (Table 3). Here, POSTN is linked to triple-negative breast carcinoma.