Flow cytometry as a tool for the prognostic assessment of human neoplasia

Flow cytometry permits the quantitative description of neoplastic cell populations from the point of view of their cytogenetic and cytokinetic features. The advances in preparation of cellular monodispersed samples allow the examination not only of in vitro and hematological, but also of surgical, biopsy, endoscopic, and lavage specimens. The analysis of cytometric DNA content has evidenced the importance of (aneu)ploidy as a remarkable tumor marker. Tumors of different sites and, in some cases, stages and/or grades are characterized by a differential occurrence of diploid vs. aneuploid cell subpopulations and by the eventual presence of different stem cell lines within the same tumor. For certain classes of neoplasms, these parameters can be used for the early recognition of neoplasia and related to disease evolution and dissemination and to the results of therapy. Flow cytometry can also be used to evaluate the fraction of (cycling) cells in the S-phase and of proliferating cells (growth fraction). The percent of S cells can be extracted from cytometric DNA content histograms. Furthermore, the method of Bromodeoxyuridine (BrdUrd) incorporation has been recently introduced into flow cytometry. BrdUrd labeling in cycling cells can be detected either by the induction of quenching or enhancement of specific DNA-dye fluorescence or by fluorescent anti-BrdUrd monoclonal antibodies. This approach has been confirmed by preliminary comparative tests on cultured cells, normal and malignant bone marrow, and human solid tumor specimens. These parameters, together with other cytometric parameters of potential importance for the cellular characterization of malignancy, offer a reliable and real time-saving tool for the prognostic assessment of human tumors and the predicting and monitoring of the results of therapy.