Purpose: We evaluated fluorescence in situ hybridization (FISH) for assessing the response to therapy in patients with superficial bladder cancer receiving bacillus Calmette-Guerin or other intravesical therapies.
Materials and methods: A total of 37 patients receiving intravesical therapy for superficial bladder cancer were enrolled in this study. Urine specimens were collected for FISH analysis just prior to the first intravesical therapy in 31 cases and just prior to or within 2 months following the last intravesical therapy in 37. FISH was done using the UroVysion probe set (Abbott Laboratories, Abbott Park, Illinois) with results considered positive if 5 or more cells demonstrated polysomy. Biopsy, cystoscopy and/or cytology results were then compared to FISH results to evaluate the usefulness of the test for monitoring intravesical therapy.
Results: Of the patients 25 had a negative and 12 had a positive post-therapy FISH result. All 12 patients with a positive post-therapy FISH result had tumor recurrence, while tumor recurrence was observed in 13 of the 25 with a negative post-therapy FISH result (HR 4.6, 95% CI 1.9 to 11.1, p <0.001). Of the patients with tumor recurrence 7 of 12 with a positive post-therapy FISH result had muscle invasive tumor and 2 of 25 with a negative post-therapy FISH result had muscle invasive tumor (HR 9.4, 95% CI 1.9 to 45.3, p = 0.001).
Conclusions: FISH appears to be useful for monitoring patients with superficial bladder cancer for the response to intravesical therapy. Patients with a positive FISH result at the end of treatment are at high risk for progression to muscle invasive bladder cancer.