Correlation of plasma CEA and CEA tissue staining in poorly differentiated colorectal cancer

A review of patients operated on for colorectal cancer disclosed poorly differentiated histologies in those whose preoperative and postoperative carcinoembryonic antigen (CEA) levels were not elevated, even in the presence of metastatic disease. CEA was, therefore, of little prognostic value or predictive of disease recurrence in these patients. The amount of CEA in tumor tissue of 17 patients with poorly differentiated colorectal cancer was estimated with the immunoperoxidase staining technique and was correlated with histology and plasma CEA levels obtained during various stages of disease. Five tumors did not stain negatively for CEA and all had predominantly poorly differentiated histologies. In all of these patients metastatic disease developed but not elevated plasma CEA levels. In contrast 12 tumors stained positively for CEA and were found to contain either differentiated areas or signet ring cells. Serial plasma CEA levels correctly monitored the postoperative courses of all 12 patients. Six of these had a relapse and all were detected by serial increases in plasma CEA. The remaining six were disease free >48 months after resection and had normal plasma CEA levels.