Clinical utility of fluorescent in situ hybridization for the surveillance of bladder cancer patients treated with bacillus Calmette-Guérin therapy.

OBJECTIVE To evaluate the use of a multiprobe fluorescent in situ hybridization (FISH) assay for determining the response of patients with high-risk superficial bladder tumour (HRSBT) to bacillus Calmette-Guérin (BCG) therapy. METHODS Bladder washing specimens from 65 HRSBT patients collected before and after BCG therapy were analyzed by FISH. Labelled probes for chromosomes 3, 7, 9, and 17 were used to assess chromosomal abnormalities indicative of malignancy. RESULTS Fifty-five of 65 (85%) patients had a positive pre-BCG FISH result; 29 (45%) patients had a positive and 36 (55%) had a negative post-BCG FISH result. Patients with a positive post-BCG FISH status had a 2.7 times higher risk for tumour recurrence than patients with a negative post-BCG FISH status (p = 0.017; 95% CI: 1.18-6.15). In addition, patients who maintained a positive FISH status before and after BCG therapy had a risk for tumour recurrence 2.96 times higher than patients whose FISH result changed from positive to negative after BCG (p = 0.02; 95% CI: 1.17-7.54). On the other hand, there was no significant difference between the risk for tumour progression in patients with a positive versus a negative post-BCG FISH result (p = 0.49). CONCLUSIONS The high percentage of positive pre-BCG FISH results suggests the need for adjuvant therapy in patients with HRSBT after the initial transurethral resection. In addition, patients with a positive post-BCG FISH result were more likely to relapse after therapy. Thus, FISH appears to be useful for the surveillance of patients with HRSBT following BCG therapy.