FAP and cancer: Beside the use of radiolabeled-FAPI tracers for a diagnostic purpose, FAP-targeting ligands labeled with alpha- or beta-emitting radioisotopes (e.g., Lutetium-177, Yttrium-90, Actinium-225) have been also introduced, exploiting their potential role as a new anti-cancer radioligand therapy (RLT), in a theranostic perspective [10,12].