Usefulness of transcription-reverse transcription concerted reaction method for detecting circulating tumor cells in patients with colorectal cancer

Purpose. The CellSearch system (Veridex, LLC) is useful for detecting circulating tumor cells (CTCs) in various carcinomas, including colorectal cancer (CRC); however, there are some problems associated with its clinical use. A transcription-reverse transcription concerted reaction (TRC) method, which is a PCR-based technique producing more stable and reliable results, because it is a more simplified process compared with the conventional techniques, has been introduced for detecting micrometastasis in some carcinomas. We aimed to demonstrate the effectiveness of TRC method in the CTC detection. Methods. We compared the two methods for the sensitivity for CTC detection using the colon cancer cell line and 42 whole-blood samples from patients with advanced or metastatic CRC. Furthermore, 25 patients with metastatic CRC were enrolled to investigate the correlation between CTC detection and prognosis in both methods. Results. The sensitivity of the TRC method was similar to that of the CellSearch system. The overall survival rate was significantly worse in the patients diagnosed as CTCpositive by the TRC method than in those diagnosed as CTC-negative; this finding was similar to the prognosis indicated by the CellSearch system. However, clinically, the TRC method could detect CTCs more rapidly and at a reduced cost compared with the CellSearch system. Conclusions. The TRC method seems to be a useful alternative to the CellSearch system for clinically detecting CTCs in patients with metastatic CRC.