On the other hand, the ASCO 2006 guidelines also admit that serum CEA test has insufficient sensitivity for detecting primary and recurrent CRC and this test may be useful as a first-line surveillance investigation in CRC patients during surgical follow-up based on serial CEA measurements, using temporal trends in conjunction with clinical, radiological and/or histological confirmation (Locker et al, 2006; Tan et al, 2009; Yamashita and Watanabe, 2009). Here, CEACAM5 is linked to colorectal carcinoma.