AIM: To detect the expression of CK20mRNA in peripheral blood of pancreatic cancer and evaluate its clinical significance. METHODS: Expression of CK20mRNA in peripheral blood was detected by fluorogenic qualitative reverse transcription-polymerase chain reaction (RT-PCR) in 40 cases of pancreatic cancer at the night before operation, in 5 cases of benign pancreatic diseases, in 5 cases of healthy individuals. The relationships were investigated between CK20mRNA expression and the clinicopathological variables, and clinical follow-up outcome in those patients with pancreatic cancer having undergone radical resection. RESULTS: Of the 40 patients with pancreatic cancer, 23 (57.5%) cases were positive for CK20mRNA expression. CK20mRNA expression was significantly correlated with lymphatic metastasis (P = 0.008), histopathological grading (P= 0.009), and pathological stage (P= 0.021); there was no significant correlation between CK20mRNA expression and age, gender, tumor diameter, and depth of invasion. The cumulative metastasis rates of patients with CK20mRNA expression were higher than those of patients with no CK20mRNA expression within 6 mo (34.7% vs5.9%, P= 0.043) or 12 mo (73.9% vs 35.3%, P= 0.02) after operation. CK20mRNA expression in peripheral blood of pancreatic cancer indicated poorer prognosis. The survival rate of patients with CK20mRNA expression was lower than that of patients with negative CK20mRNA expression (Log-Rank = 13.31, P= 0.0003). CONCLUSION: CK20mRNA is a sensitive and specific molecular marker for the detection of micrometastasis in peripheral blood of patients with pancreatic cancer. The CK20mRNA expression in peripheral blood is correlated with biological characteristic of pancreatic cancer. It can help to predict the prognosis of pancreatic cancer after operation, and to determine which patient will benefit from aggressive adjuvant therapies. METHODS: Expression of CK20 mRNA in peripheral blood was detected by fluorogenic qualitative reverse transcription-polymerase chain reaction (RT-PCR) in 40 cases of pancreatic cancer at the night before operation, in 5 cases of benign pancreatic diseases, in 5 cases of healthy individuals. The relationships were investigated between CK20 mRNA expression and the clinicopathological variables, and clinical follow-up outcome in those patients with pancreatic cancer having undergone radical resection. RESULTS: Of the 40 patients with pancreatic cancer, 23 (57.5%) cases were positive for CK20 mRNA expression. CK20 mRNA expression was significantly correlated with lymphatic metastasis (P = 0.008), histopathological grading (P = 0.009) 0.021); there was no significant correlation between CK20 mRNA expression and age, gender, tumor diameter, and depth of invasion. The cumulative metastasis rates of patients with CK20 mRNA expression were higher than those of patients with CK20 mRNA expression within 6 mo (34.7% vs 5.9%, P = 0.043) or 12 mo (73.9% vs 35.3%, P = 0.02 ) survival rate of patients with CK20 mRNA expression was lower than that of patients with negative CK20 mRNA expression (Log-Rank = 13.31, P = 0.0003). CONCLUSION: CK20 mRNA is a sensitive and specific molecular marker for the detection of micrometastasis in peripheral blood of patients with pancreatic cancer. The CK20 mRNA expression in peripheral blood is correlated with biological characteristic of pancreatic cancer. It can help to predict the prognosis of pancreatic cancer after operation, and to determine which patient will benefit from aggressive adjuvant therapies.