An approach based on i.v. injection of MMP12-engineered ECFCs, able to impair tumor progression (therapy), and on the labelling of ECFC with 111In-oxine for molecular imaging of primary and metastatic tumor masses (diagnosis), provides a new and promising MMP12 theranostic approach to human melanoma and to future cancer medicine for all the tumor displaying uPAR-dependent cancer progression. This evidence concerns the gene MMP12 and melanoma.