CEACAM5 and neoplasm: This phenomenon has been documented previously by Boudousq et al. during RIT treatment of small volume carcinomatosis using two different 212Pb-IgG; the 212Pb-35A7 mAbs (anti-carcinoembryonic antigen) were less efficient than 212Pb-trastuzumab (anti-HER2), although the dose absorbed by the tumor was higher for 212Pb-35A7 28.