CEACAM5 and colorectal carcinoma: Carcinoembryonic antigen (CEA) is of proven benefit in prognosis and follow-up, but has limited sensitivity (30–40%) for early CRC (Fletcher, 1986), whereas serial faecal occult blood testing is proven to reduce CRC mortality but suffers from significant false-negative and false-positive rates (Hardcastle et al, 1989; Mandel et al, 1993; Kronberg et al, 1996).