The biodistribution results were compared with those obtained in six patients with similar clinical status and injected with directly labeled 111In-labeled anti-CEA F(ab’)2. Tumor uptake measured from resected tumors using the two-step approach was 1.8–17.5% injected dose/kg and not significantly lower than that found in the six patients injected with directly labeled antibody (5.5–30.2% injected dose/kg). Here, CEACAM5 is linked to neoplasm.