Determination of circulating tumor cells for prediction of recurrent colorectal cancer progression.

BACKGROUND/AIMS: The aim of this study is to determine the relationship between circulating tumor cells (CTCs) and response to chemotherapy in patients with unresectable metastatic colorectal cancer.

METHODOLOGY

CTCs of twelve consecutive patients with K-ras wild type colorectal cancer with synchronous and/or metachronous unresectable metastatic lesions were measured by the cell search system between January 2009 and December 2010. CTCs were measured before and after chemotherapy. The regimen consisted of four courses (three months) of SOX (TS-1+L-OHP) + panitumumab.

RESULTS

Four patients (33%) had no detectable CTCs before chemotherapy. For these patients, no CTCs were detected after chemotherapy and their serum carcinoembryonic antigen (CEA) levels decreased after chemotherapy. Four of the other eight patients with positive CTCs had no detectable CTCs after chemotherapy and their serum CEA levels decreased after chemotherapy. The other four of eight patients with positive CTCs continued to have CTCs after chemotherapy and all four patients died of cancer within eight months after starting chemotherapy. On the other hand, all eight patients without CTCs after chemotherapy were alive over a year after starting chemotherapy.

CONCLUSIONS

CTCs may be able to predict the response to chemotherapy in patients with unresectable metastatic colorectal cancer.