While cystatin C has been reported to promote tumor growth and therapy resistance by enhancing cancer cell survival during radiotherapy and facilitating tumor repopulation11, it has also demonstrated tumor-suppressive properties, mainly through its inhibitory action on cysteine cathepsins, enzymes that regulate extracellular matrix (ECM) degradation and remodeling, thereby inhibiting tumor cells invasion and metastasis12. This evidence concerns the gene CST3 and cancer.