Cancer cells enter the circulation and attach to endothelial cells to pass through them and migrate over a distance to enter the tissue of the metastatic organ to proliferate there. In the same way, neutrophils drift in blood and adhere loosely to adhesive molecules on the endothelial cells in an inflamed area. They roll along the endothelial cells and then adhere closely to the endothelial cells to penetrate vessel wall. Neutrophils can destroy the basement membrane and migrate over a distance to fight against foreign bodies. Thus, the process that both of them follow is quite the same. Neutrophil elastase (NE) is a neutral serine protease which has broad substrate specificity under the physiological conditions, and its excessive production results in digestion of not only elastin, but also other extracellular matrix proteins. This minireview summarizes our recent experimental and clinical studies on NE/NE inhibition and cancer/cancer treatment based on our original view point.