Flow cytometry detection and evaluation of bladder tumors

The diagnosis and classification of bladder cancer are based primarily on histologic and cytologic light microscopy. The significant cytologic alternations are abnormal (increased) DNA content and structural changes in chromatin. Measurements of DNA content carried out by flow cytometry on suspensions of tumor cells and bladder irrigation specimens correlate well with clinical and biopsy findings. Badalament et al (Badalament RA, Kimmel M, Gay H, et al. Cancer 1987;59:2078-2085) reported that a single bladder wash flow cytometry correctly detected 83% of bladder cancers. The technique is most sensitive in detecting early, in situ, and superficially invasive carcinoma. In 100 urologic patients with non-neoplastic disease of the bladder, Klein et al (Klein FA, Herr HW, Sogani PC, et al. J Urol. 1982;127:946-948) reported only two false-positive examinations. Flow cytometry appears to be at least as valuable as conventional urinary cytology, without the need of an experienced cytopathologist. However, as specimens must be collected by bladder irrigation via catheter or cytoscope, the technique is most suitable not for population screening, but in monitoring high-risk populations: industrial workers or others exposed to carcinogens, persons with a history of urothelial tumors, and adult patients referred for urologic examinations because of hematuria, unexplained, recurrent cystitis, or other urologic symptoms. DNA flow cytometry also has been valuable in monitoring the conservative treatment of bladder cancer and of predictive value in the intravesical bacille Calmette-Guérin treatment of superficial carcinomas of the bladder. Dual parameter measurements of DNA content and antigen expression are now under evaluation, as are measurements of chromatin structure alteration, metabolism, and proliferative rate. These promise to discriminate subsets of bladder cancer that may be predictive of clinical behavior.