In advanced‐stage CRC, the AUC of anti‐FIRΔexon2 Abs with CEA and anti‐p53 Abs (0.877) was higher than that of anti‐FIRΔexon2 Abs +3 marker (anti‐p53 Abs, CA19‐9 and CEA; 0.874) or anti‐FIRΔexon2 Abs + CEA (0.862) or anti‐FIRΔexon2 Abs + CEA + CA19‐9 (0.848; Figure 4D). Here, CEACAM5 is linked to colorectal carcinoma.