CEACAM5 and neoplasm: Although utilizing biodistribution data from using a radioiodine labeled antibody fragment to estimate biodistribution of a radiometal labeled fragment was not performed, one can imagine based on the immunohistochemical staining pattern that a radiolabeled engineered antibody with modest tumor penetration, as demonstrated in this study with the anti-CEA scFv-Fc (H310A) antibody, may have applications for radioimmunotherapy.