BACKGROUND: We evaluated the feasibility of CEA/CK20 mRNA and CEA/CA19-9 proteins as tumor markers for colorectal cancer by detecting tumor-specific mRNAs in circulating tumor cells and secreted tumor-specific proteins in the peripheral blood of colorectal cancer patients. PATIENTS AND METHODS: Peripheral blood was obtained from 23 healthy volunteers and 46 colorectal cancer patients on the day of initiation of adjuvant chemotherapy after surgery (stages I-III, n = 27) or on the first day of chemotherapy after diagnosis (stage IV, n = 19). Levels of CEA/CK20 mRNA in peripheral blood mononuclear cells (PBMCs) were determined with quantitative real-time reverse transcription polymerase chain reaction, and serum CEA/CA19-9 protein levels were determined by radioimmunoassay. RESULTS: The detection sensitivity of CK20 mRNA was approximately 1 tumor cell in 1 × 10(7) PBMCs, and that of CEA mRNA was approximately 1 tumor cell in 1 × 10(6) PBMCs. Patients with stage IV colorectal cancer had higher levels of CEA mRNA, CK20 mRNA, and serum CEA than patients at stages I-III. Peripheral blood CEA mRNA levels were predictive of overall survival, while serum protein levels of CEA and CA19-9 had no predictive value. CONCLUSION: Peripheral blood CEA mRNA is a useful marker of overall survival in colorectal cancer patients, that is sensitive and specific.
BACKGROUND: We evaluated the feasibility of CEA/CK20 mRNA and CEA/CA19-9 proteins as tumor markers for colorectal cancer by detecting tumor-specific mRNAs in circulating tumor cells and secreted tumor-specific proteins in the peripheral blood of colorectal cancerpatients. PATIENTS AND METHODS: Peripheral blood was obtained from 23 healthy volunteers and 46 colorectal cancerpatients on the day of initiation of adjuvant chemotherapy after surgery (stages I-III, n = 27) or on the first day of chemotherapy after diagnosis (stage IV, n = 19). Levels of CEA/CK20 mRNA in peripheral blood mononuclear cells (PBMCs) were determined with quantitative real-time reverse transcription polymerase chain reaction, and serum CEA/CA19-9 protein levels were determined by radioimmunoassay. RESULTS: The detection sensitivity of CK20 mRNA was approximately 1 tumor cell in 1 × 10(7) PBMCs, and that of CEA mRNA was approximately 1 tumor cell in 1 × 10(6) PBMCs. Patients with stage IV colorectal cancer had higher levels of CEA mRNA, CK20 mRNA, and serum CEA than patients at stages I-III. Peripheral blood CEA mRNA levels were predictive of overall survival, while serum protein levels of CEA and CA19-9 had no predictive value. CONCLUSION: Peripheral blood CEA mRNA is a useful marker of overall survival in colorectal cancerpatients, that is sensitive and specific.