Fluorescence in situ hybridization for detecting transitional cell carcinoma: implications for clinical practice

OBJECTIVE To determine the diagnostic sensitivity of genetic studies using fluorescence in situ hybridization (FISH) for detecting both new and recurrent cases of transitional cell carcinoma (TCC) in a routine clinical practice setting, as bladder cancer has a significant risk of recurrence and progression to invasive disease and thus sensitive surveillance testing is very important. PATIENTS AND METHODS FISH was performed using the UroVysionTM kit (Vysis Inc., Downers Grove, IL, USA) Consecutive patients were assessed using FISH, both to evaluate those with a history of TCC or with suspicious symptoms, and the FISH results were compared with concurrent biopsy and cytological assessments. RESULTS In all, 521 consecutive FISH tests from 300 patients were evaluated; 47% had a history of bladder cancer and 53% had suspicious symptoms. Of the 521 FISH tests, 24% were positive; concurrent cytology was available for 84% of the FISH tests, with a concordance rate of 78% (6% were positive for both and 72% were negative by both tests). For the discordant cases, FISH was positive and cytology negative in 21% of cases, and cytology was positive with a negative FISH for 1%. In all, 99 FISH tests had concurrent biopsy data. Of the 44 cases histologically positive for TCC, 32 were FISH‐positive, resulting in an overall sensitivity (95% confidence interval) of 73 (60–88)%. FISH detected 95% of cases with high‐grade carcinoma, while only seven of these 17 were positive by concurrent cytological assessment. FISH detected 56% and cytology detected 32% of low‐grade lesions. FISH detected all nine new cases with positive histology. Overall, the specificity of FISH was 65 (53–78)%. Of 112 patients with previous TCC, 28 had a recurrence; 22 of these had positive FISH results. CONCLUSION FISH analysis has a high sensitivity for detecting new cases of TCC, as well as recurrences. From the present data FISH is considerably more sensitive and only slightly less specific than cytology in diagnosing TCC. Therefore, we recommend FISH as a useful initial diagnostic tool in patients suspected of both new and recurrent TCC.