M5A mAb is also an anti-CEA mAb and was radiolabeled with 124I for the detection of CEA positive colorectal cancer that has spread to the liver (Clinicaltrials.gov identifier NCT 03993327) or with 64Cu for the diagnosis of CEA positive rectal cancer (Clinicaltrials.gov identifier NCT 05245786) or in gastrointestinal, lung, medullary thyroid and breast cancers (Clinicaltrials.gov identifier NCT 02293954). The gene discussed is CEACAM5; the disease is breast cancer.