RAIT using directly radiolabeled anti-carcinoembryonic antigen (CEA) mAb has shown promising clinical results in metastatic medullary thyroid carcinoma (MTC) and metastatic colon cancer (5, 6), but pretargeting of CEA-expressing tumors has demonstrated a more favorable therapeutic index and antitumor efficacy in preclinical MTC and colorectal cancer (CRC) models (7, 8) and clinical feasibility in MTC and small-cell lung cancer (SCLC) (9, 10). The gene discussed is CEACAM5; the disease is medullary thyroid gland carcinoma.