[Circulating tumor cells: detection, characterization and clinical impact]

The metastatic process generates circulating tumor cells (CTCs) and disseminated tumor cells (DTCs) in bone marrow and other organs which can remain as occult metastases. Various methods and systems have been developed to allow the isolation and identification of those cells but major technical limitations still exist. Research on CTCs is a nevertheless tremendously growing field of cancer research because of their potential clinical applications. CTCs indeed convey predictive information for the development of metastasis and recurrence, and prognostic information regarding patient survival. CTCs enumeration could also be used to monitor the effectiveness of adjuvant treatments. Moreover, enhancing our basic understanding of the metastatic process, CTCs, and DTCs in particular, are thought to contain subpopulations of cells with stem cells properties that would be responsible for relapses.