Fluorescence in situ hybridization as prognostic predictor of tumor recurrence during treatment with Bacillus Calmette-Guérin therapy for intermediate- and high-risk non-muscle-invasive bladder cancer.

A significant number of patients with intermediate- or high-risk bladder cancer treated with intravesical Bacillus Calmette-Guérin (BCG) immunotherapy are non-responders to this treatment. Since we cannot predict in which patients BCG therapy will fail, markers for responders are needed. UroVysion ^® is a multitarget fluorescence in situ hybridization (FISH) test for bladder cancer detection. The aim of this study was to evaluate whether FISH can be used to early identify recurrence during treatment with BCG. In a multicenter, prospective study, three bladder washouts at different time points during treatment (t ₀  = week 0, pre-BCG, t ₁  = 6 weeks following TURB, t ₂  = 3 months following TURB) were collected for FISH from patients with bladder cancer treated with BCG between 2008 and 2013. Data on bladder cancer recurrence and duration of BCG maintenance therapy were recorded. Thirty-six (31.6%) out of 114 patients developed a recurrence after a median of 6 months (range 2-32). No significant association was found between a positive FISH test at t ₀ or t ₁ and risk of recurrence (p = 0.79 and p = 0.29). A positive t ₂ FISH test was associated with a higher risk of recurrence (p = 0.001). Patients with a positive FISH test 3 months following TURB had a 4.0-4.6 times greater risk of developing a recurrence compared to patients with a negative FISH. Patients with a positive FISH test 3 months following TURB and induction BCG therapy have a higher risk of developing tumor recurrence. FISH can therefore be a useful additional tool for physicians when determining a treatment strategy.