Bladder irrigation specimens provide a sampling of the entire bladder urothelium and are the most practical sample for longitudinally monitoring patients. This study presents cross-sectional fluorescence in situ hybridization (FISH) analyses with correlated DNA cytometry data on 76 patients monitored for recurrent bladder tumors. FISH probes complementary to centromeric satellite sequences for chromosomes 1, 7, 9, l l , 15, and 17 were used. Aberrations in copy number were observed for chromosomes 1, 7, 11, and 17 principally in patients with aneuploid tumors. Monosomy of chromosome 9 was observed in 39% of the diploid and 31% of the specimens with high hyperdiploid fraction. Significantly, 24% of patients with a history of bladder cancer but with no clinical evidence of disease exhibited monosomy of chromosome 9. This suggests a persistent and significantly large population of abnormal cells in the absence of clinical evidence of disease. Loss of chromosome 9 relative to DNA ploidy was observed in 24% of patients with no evidence of disease, in 59% of patients with tumor, and in 79% of patients with histologically confirmed transitional cell carcinoma, grades 1-3. Loss of chromosome 15 was also observed in a large percentage of patients. Loss of chromosome 15 was observed in 41% of specimens from patients in whom no tumor was seen, in 38% of specimens from patients with tumor, and in 67% of specimens from patients with histologically confirmed transitional cell carcinoma. Results of this study document the use of bladder irrigation specimens as a specimen source for FISH analyses. The ability to perform FISH analyses on bladder irrigation specimens from patients followed for recurrent bladder cancer is important in that it offers the potential of studying early genetic events as well as correlating specific aberrations with progression and recurrence. 0 1994 Wiley-Liss, Inc.Key terms: Bladder neoplasia, DNA cytometry, tumor markers, chromosomes Quantitative measurements of bladder tumor DNA content have been performed for over a decade and provide limited clinical information. The maximal utility of DNA cytometry has been in stratifying grade 2 superficial (Ta, TI, TIS) tumors with respect to risk of progression and in monitoring intravesical therapy (26). Measurement of DNA content by flow or image cytometry is limited in sensitivity to the addition or loss of several whole chromosomes and does not fully provide the individual prognostic information on progression and recurrence so needed in the clinical management of patients with bladder cancer.The detection of numerical chromosomal aberrations by fluorescence in situ hybridization (FISH) has been shown to be useful in the study of bladder cancer. Aberrations involving chromosomes 1, 3, 5, 7, 9,
