Detection of circulating oesophageal squamous cancer cells in peripheral blood and its impact on prognosis

Background: Many studies have attempted to detect cancer cells using the reverse transcription-polymerase chain reaction (RT-PCR) for specific mRNAs. None has examined the correlation between the presence of circulating oesophageal cancer cells in peripheral blood and long-term outcome. Methods: Blood samples were obtained on admission, and before, during and after operation from 70 patients with squamous oesophageal cancer who had complete clinicopathological records and who underwent curative oesophagectomy between June 1997 and June 2000. RT-PCR for mRNA encoding squamous cell carcinoma antigen (SCCA mRNA) was used to detect oesophageal cancer cells in peripheral blood. Results: Twenty-three patients (33 per cent) were positive for SCCA mRNA on admission and 17 of these patients developed recurrent disease. SCCA mRNA on admission correlated with the depth of turnout invasion (P<0.001) and with venous invasion (P<0.001). Eleven of 24 patients with a positive intraoperative result were positive for SCCA mRNA only during operation, of whom seven also developed recurrence. Conclusion: RT-PCR for SCCA mRNA can detect oesophageal cancer cells in peripheral blood. The presence of such cells in blood samples obtained on admission or during operation is a useful predictor of outcome in patients with oesophageal squamous cell carcinoma.