Flow cytometric evaluation of bladder cancer: recommendations of the NCI flow cytometry network for bladder cancer

The National Cancer Institute-supported Flow Cytometry Network for Bladder Cancer concluded that when properly used, DNA flow cytometry of bladder irrigation specimens can be a clinically useful laboratory procedure to monitor patients with bladder cancer. It recommended the use of this technique in managing patients with low-stage disease, particularly flat carcinoma in situ. The method has limited value in managing patients with high-stage (i.e., muscle-invasive) carcinoma; it is not recommended for screening subjects in the absence of a clinical suspicion of or a history of bladder tumors. DNA histograms alone are not sufficient for diagnosis or clinical action but require correlation with other clinical information. Bladder irrigation specimens collected during cystoscopy or by vigorous barbotage via a number 18 Foley catheter may be processed for flow cytometric analyses. Criteria for sampling adequacy have been established and are presented in this report. Optimal results are obtained with fresh specimens that are stained and examined promptly after collection. Preservation procedures are described for cases in which fresh specimens cannot be evaluated. Used with appropriate quality-control measures, commercially available flow cytometers can provide clinically useful information. Staining protocols using propidium iodide are recommended by the Network. Staining protocols are described for isolated nuclei and whole cells (see Appendix). The presence of bladder cancer is signaled by the identification of cell populations with clearly aneuploid DNA content. Quality-control measures and issues of inter- and intralaboratory differences in histogram configuration and analysis must be considered in the interpretation of results. Although the Network participants recognize the potential value of additional markers, these were not evaluated.