Cytokeratin serum biomarkers in patients with colorectal cancer

Background: Circulating cytokeratins have shown to be important for management of patients with lung cancer. Here we investigated their role for differential diagnosis, therapy monitoring and prognosis in colorectal cancer (CRC). Patients and Methods: Pretherapeutic levels of cytokeratin-19 fragments (CYFRA 21-1), carcino-embryonic antigen (CEA) and cancer antigen (CA) 19-9 were measured in 42 patients with CRC, 45 with benign colorectal diseases and 51 healthy controls. Furthermore, courses of CYFRA 21-1, tissue polypeptide antigen (TPA), tissue polypeptide specific antigen (TPS), M30-antigen, CEA and CA 19-9 were analyzed in prospectively collected sera of 15 patients with CRC during primary chemotherapy and were correlated with therapy response and overall survival (OS). Results: Similar to CEA and CA 19-9, CYFRA 21-1 was significantly elevated in serum from patients with CRC (median 2.1 ng/ml) as compared with healthy (1.2 ng/ml; p<0.0001) and benign gastrointestinal controls (1.7 ng/ml; p=0.0178) and showed stage dependency in CRC (p=0.0118). CYFRA 21-1 correlated with CEA in benign diseases and CRC but not with CA 19-9. The best discrimination between healthy controls and patients with CRC was achieved by combination of CYFRA 21-1 and CA 19-9 (area under the curve; AUC=86.7%), while the combination of CEA and CA 19-9 discriminated best between benign diseases and CRC (AUC=73.9%). In CRC patients during primary chemotherapy, levels of cytokeratins CYFRA 21-1, TPA, TPS, CEA and CA 19-9 tended to be higher in patients with poor response to therapy and with poor prognosis. Conclusion: Cytokeratins are elevated in patients with CRC and show some association with response to primary therapy and prognosis.