CEA mRNA identification in peripheral blood is feasible for colorectal, but not for gastric or pancreatic cancer staging

OBJECTIVE: It has been suggested that the molecular identification of cancer cells in the circulation may be useful in predicting the presence of micrometastasis in several cancer types. The aim of the present study was therefore to assess the feasibility of CEA mRNA identification in blood for diagnosing and staging colorectal, gastric and pancreatic cancer. METHODS: We studied 16 control subjects, 69 patients with colorectal (CRC), 30 with gastric (GC), 27 with pancreatic cancer (PC) and 8 with benign diseases of the pancreatobiliary tree. At diagnosis CEA mRNA was identified in peripheral blood by means of a RT-PCR procedure. RESULTS: The specificity of this test in control subjects was 94%, and its sensitivity in identifying CRC, GC and PC were 34, 37 and 41%, respectively. False-positive findings were recorded in 25% patients with benign diseases. No association was found between CEA mRNA and stage in patients with GC or PC. In CRC patients, positive CEA mRNA findings were correlated with local spread (chi(2) = 14.6, p<0.01), lymph node (chi(2) = 18.95, p<0.001) and distant metastasis (chi(2) = 11.3, p<0.001). In these cases, CEA mRNA, but not CEA, was entered in stepwise discriminant analysis to classify the presence of lymph node metastasis. CONCLUSIONS: The molecular detection of micrometastasis in the blood by means of CEA mRNA identification is feasible for colorectal, but not for gastric or pancreatic cancer staging. Further studies are needed in order to define the clinical utility of this marker also in follow-up protocols.