Disseminated tumor cells: a clinical help or over-information?

Abstract

Most breast cancer patients do not die from their primary tumor but rather from metastases developing in distant organs. Cells from the tumor can already leave from the primary tumor when it is still below the limit of detection of mammography and it is not known at what time point these cells can settle and regrow. In addition, diagnostic and therapeutic approaches might contribute to mobilizing cells from the primary tumor since it has been shown that manipulations of the primary tumor may seed cells into the circulation [1–3]. In order to leave the tissue, cells need to detach from the surrounding cells which physiologically occurs during cell division. This may be one reason, why tumors with a high cell division rate have a higher metastatic capacity. During detachment cell adhesion molecules such as the Epithelial Cell Adhesion Molecule (EpCAM) are down regulated [4]. EpCAM is a cell surface adhesion protein that is frequently expressed at a high level on most solid tumor types, including prostate, breast, colon, gastric, ovarian, pancreatic, and lung cancer [5,6]. Screening mammography, aiming at detecting early tumors has not yet shown convincing results [7,8] and it is discussed whether it rather extends the period of disease than extending life time [9]. We have, therefore, investigated the effect of diagnostic mammography on the release of epithelial cells from normal and malignant tissue and the fate of the released cells in blood circulation.