Circulating tumor cells in colorectal cancer: detection methods and clinical significance

Colorectal cancer is one of the most frequently diagnosed malignancies in both men and women. Although curative resection is the major treatment option, approximately half of all patients eventually develop distant metastases. Thus, the need for early detection of occult metastases has led to extensive investigation with regard to the detection of disseminated tumor cells in biological fluids, including peripheral blood or bone marrow of cancer patients. In this review, we summarize the methods currently implemented for disseminated tumor cell detection in colorectal cancer. In addition, we discuss the pitfalls of each method and the future perspectives in the development of an easily applied, quick and inexpensive method which will enable the reliable detection of circulating tumor cells with optimal sensitivity and specificity.