Role of carcinoembryonic antigen in the management of advanced colorectal cancer.

Carcinoembryonic antigen (CEA) was first described more than three decades ago, when its presence was demonstrated in fetal gut tissue and in tumors from the gastrointestinal tract. Subsequently, CEA was detected in the circulation of patients and recognized as a serum marker for colorectal cancer. In the early diagnosis of disease recurrence following surgical resection, a serial increase in CEA level is the first evidence of tumor. In patients with disseminated tumors, serial determinations are useful for monitoring response to therapy. Carcinoembryonic antigen values decrease with effective treatment, while they increase with disease refractory to therapy or progressive metastases, yet the utility of CEA in the management of patients with advanced colorectal cancer remains controversial.