MMP9 and metastatic malignant neoplasm in the lymph nodes: The meta-analysis performed by Jiang et al. (the materials of 41 experimental studies, including 6517 BC patients, were used) not only shows the association of increased expression of MMP9 with a shorter overall survival of BC-affected women but also the association of high expression of MMP9 with other BC clinical (clinicopathological) signs such as histological grade, clinical stage, larger tumor sizes, and lymph node metastasis [37].