Detection of breast cancer cells in the bone marrow or peripheral blood: Methods and prognostic significance

Tumor cells can reach every anatomic district, organ and tissue through the peripheral blood circulation. Tumor cell shedding is considered an early e vent in the multi-phase process of metastasis, and the possibility of detec ting tumor cells in the bloodstream and/or bone marrow before clinical evid ence of distant metastases needs to be explored. The use of new sophisticat ed diagnostic and investigative techniques has boosted the study of tumor c ell contamination of bone marrow and peripheral blood. Molecular techniques , such as reverse-transcriptase polymerase chain reaction, may be useful to ols to reach this target, but, today, immunocytochemistry is still consider ed the gold standard to assess new techniques to detect isolated tumor cell s in hematopoietic tissue. Little is known about the biology of isolated tu mor cells in the peripheral blood or bone marrow. Two crucial points need t o be evaluated: the identification of specific markers of breast cancer cel ls with clonogenic potential and their biologic properties, and the prognos tic impact of the detection of isolated tumor cells in the bone marrow or p eripheral blood stem cell collections.