The advantage of circulating tumor cells over serum carcinoembryonic antigen for predicting treatment responses in rectal cancer

Aim: The objective of this study was to investigate the clinical significance of circulating tumor cells (CTCs) on the evaluation and prediction of treatment responses in rectal cancer patients compared with serum carcinoembryonic antigen (CEA). Materials & methods: Both CTCs and CEA levels of 103 rectal cancer patients (66 with stage II-III and 37 with recurrence or metastasis) were analyzed before and after chemoradiotherapy. CTCs were detected using EpCAM magnetic bead-based enrichment combined with cytometric identification. Results: CTCs were detected in all patients while no tumor cells were found in healthy controls. CTC levels in metastatic patients were significantly higher than those with recurrence or stage II-III rectal cancer. There is a close relationship between CTC levels and treatment outcomes but serum CEA did not have any correlation. Conclusion: CTCs are promising markers for the evaluation and prediction of treatment responses in rectal cancer patients, superior to the conventional tumor marker CEA.