CEA in Activated Macrophages. New Diagnostic Possibilities for Tumor Markers in Early Colorectal Cancer

Background: Serum tumor markers show low sensitivity, making them unsuitable for early detection of cancer. Activated macrophages (AM) from peripheral blood can accumulate tumor marker substances and facilitate early detection in prostate cancer. Here it was investigated whether carcinoembryonic antigen (CEA)-containing macrophages (CEACM) can be used to detect colorectal cancer (CRC) at earlier stages than can serum CEA. Patients and Methods: Peripheral blood was collected from patients with CRC (n=48), inflammatory colorectal disease (n=5) and from healthy controls (n=18). After separating and labeling AM with CD14-APC/CD16-FITC, AM were intracellularly labeled with anti-CEA antibody and flow cytometrically analyzed. Serum CEA and C-reactive protein (CRP) were measured. Results: The fraction-size of CEACM discriminated between controls and CRC patients, irrespective of AJCC stage (AJCC stage I-IV p <= 0.0001). Serum CEA values were significantly elevated in AJCC stage II, III and IV (p=0.02, 0.006 and <0.0001, respectively). Combining CEACM with CRP levels separated CRC from inflammatory colorectal disease. Conclusion: CEACM combined with CRP appears to have diagnostic potential in early CRC.