Breast Cancer Patients Before, During or After Treatment: Circulating Tumor Cells in Peripheral Blood Detected by Multigene Real-Time Reverse Transcriptase-Polymerase Chain Reaction

Disseminated tumor cells are considered the main cause for disease progression and metastatic relapse in breast cancer. Histological and immunological protocols are routinely used to detect metastatic cancer cells in lymph node and more recently in bone marrow specimens. In addition to conventional pathology procedures, polymerase chain reaction (PCR) has already been proposed over 10 years ago as a sensitive tool to detect micrometastatic cells by Ghossein and Rosai (1996). A continuously growing number of studies have demonstrated the use of reverse transcriptase polymerase chain reaction (RT-PCR) to detect neoplastic mammary cells in sentinel and axillary lymph nodes, in bone marrow and peripheral blood. Several RNA markers have been described, including tumor associated transcripts (e.g., carcinoembryonic antigen (CEA) Gerhard et al., 1994), transcripts of epithelial tissue-specific genes (e.g., cytokeratin 19 and 20 Slade et al., 1999), mucin family members (e.g., MUC1 de Cremoux et al., 2000) and the breast tissue-specific gene Mammaglobin (hMAM) by Zach et al. (1999).