Detection and clinical relevance of tumor cells in blood and bone marrow of patients with colorectal cancer.

In colorectal cancer, the predictive value of the currently used staging method is limited. Therefore, many parameters have been studied to improve the prediction of final clinical outcome, including several aspects of the primary tumor that are associated with its aggressiveness and the capacity of the host response. A more direct approach to predict the metastatic potential of a tumor may be the determination of limited disseminated disease at an early stage before it becomes clinically evident. Very sensitive techniques have been developed to detect single or very few tumor cells that have been disseminated into lymph nodes, blood, bone marrow and the peritoneal cavity. This review describes the advantages and disadvantages of the main detection techniques and discusses the current state of clinical relevance of disseminated tumor cells in patients with colorectal cancer.