DNA cytometry and chromosome 9 aberrations by fluorescence in situ hybridization of irrigation specimens from bladder cancer patients

Objectives: To determine the sensitivity and specificity of combining fluorescence in situ hybridization (FISH) measurement of chromosome 9 and DNA cytometry of bladder irrigation specimens in the detection of bladder cancer. Methods: Bladder irrigation specimens were obtained from 37 normal control patients and 317 bladder cancer patients during cystoscopic examinations. Bladder cancer patients were sampled in the absence of observable tumor (256 specimens) and concurrently with tumor (204 specimens). Chromosome 9 copy number was determined on a cellular basis by FISH, and cellular DNA content was determined by Feulgen DNA staining and image cytometry. Results: Sensitivity of chromosome 9 FISH was 42% for all tumors and was not correlated to transitional cell carcinoma tumor grade, while the sensitivity of DNA cytometry was 55% and improved with increasing grade from 38% for grade 1 to 90% for grade 3 tumors. The results of FISH and DNA cytometry were combined, resulting in specificity of 92% and sensitivity of 69% for grade 1, 76% for grade 2, and 97% for grade 3 tumors. Conclusions: The lack of increase with grade in the percentage of positive specimens by FISH supports the hypothesis that chromosome 9 aberrations are critical events in bladder tumorigenesis for many patients. These data demonstrate the presence of cells in irrigation specimens with specific genomic lesions of chromosome 9 and DNA content. Combining FISH on chromosome 9 and DNA cytometry provides an in sensitivity to transitional cell carcinoma over either test alone.