CTSS and neoplasm: TAMs secrete extracellular material (ECM)-degrading enzymes, such as cathepsins, matrix metalloproteinases (MMPs), and serine proteases, which can proteolytically degrade the intracellular matrix, and thus loosen the fibrous connective tissue surrounding the tumor, enabling tumor cells to escape from the tumor mass and allow local invasion or entry to the circulation to initiate dispersion to a distant site [11].