ABSTRACT
Several different assays have been developed to detect DTC in breast cancer and other types of carcinomas. One major approach to identify DTC is immunocytochemical staining with monoclonal antibodies against epithelial or
tumor-associated antigens.4-7 To date, cytokera - tins have become the most widely accepted protein markers for the detection of epithelial tumor cells in mesenchymal tissues such as BM, blood or lymph nodes.8-10 However, different staining techniques can result in specificity variations.11,12 Several international organizations have therefore recognized the need for stand - ardization of the immunocytochemical assay and for its evaluation in prospective studies (see www.dismal-project.eu).13,14
Immunocytochemical analysis is usually used in combination with density gradient centrifugation, immunomagnetic procedures or size filtration methods to enrich tumor cells prior to their detection.15-18 One way to improve current detection assays for single tumor cells is to develop better tumor cell enrichment procedures using improved density gradients19 and antibody-coupled magnetic particles.20-22 At present, it is unclear whether these new enrichment techniques provide more clinically relevant information than the standard density gradient procedure used to isolate the mononuclear cell fraction (Figure 7.1).
