Background: The circulating tumor cells of solid tumors, especially in colorectal cancer has been of great interest in medical research in the last and new century.
Methods: A literature review of recent data for the preparation of a proposal for clinical applications.
Results: Starting with the detection of circulating cancer cells in histological sections, lymph nodes, bone marrow and peripheral blood have recently become the primary samples for these investigations. Following microscopic morphology, new methods were and are being developed continuously including rare cell enrichment and detection techniques like fluorescence microscopy, flow cytometry, RT-PCR and methylated DNA PCR. The sensitivity of these assays reaches down to the concentration of 1 tumor cell/ml blood. A lot of different epithelial markers were targeted with these techniques e.g. cytokeratins, EGFR, CEA, and EMA. Clinically, circulating tumor cells were found as independent prognostic factors in lymph nodes and bone marrow. In blood, their presence appears to be an early marker for recurrence and relapse. The change in their quantitative number is supposed to reflect the chemotherapeutic sensitivity and metastatic growth activity of the tumor.
Conclusions: The detection of circulating tumor cells in bone marrow and lymph nodes is of clinical significance. Their presence in peripheral blood and therapeutic applications need further clarification.
Copyright 2003 S. Karger AG, Basel