Breast tumors with an overexpression of MMPs are associated with invasion and metastases.9 In our analysis of clinical data sets taken from the KM-Plotter database,36 we show that significantly increased expression levels of MMP-2 (P=1.5e−6), MMP-9 (P=0.027), and MMP-14 (P=0.00051) were predictive of a decreased RFS in chemotherapy treated ER- human breast cancer patients (n=211). This evidence concerns the gene MMP9 and breast neoplasm.