FISH reflects response to bladder cancer therapy

The response of superficial bladder cancer to intravesical therapy can be accurately determined by urinary fluorescence in situ hybridization (FISH), according to a report in the February issue of The Journal of Urology.

“Our study clearly shows that patients with a positive post-therapy FISH result are at high risk of having progressed to muscle-invasive tumor,” Dr. Kevin C. Halling from Mayo Clinic and Foundation, Rochester, Minnesota told Reuters Health. “Consequently, I think that these patients should be seriously considered as candidates for cystectomy. Delaying cystectomy puts these patients at significant risk of developing metastatic disease.” Dr. Halling and colleagues assessed the ability of FISH to determine the response of 37 patients with superficial bladder cancer to BCG and other intravesical therapies. Urinary specimens were tested before and after therapy, and FISH results were considered positive if > 5 cells demonstrated polysomy.Patients with a positive pre-therapy FISH result had 3.3-times greater risk for tumor recurrence than patients with a negative pre-therapy result, the researchers report. For patients with a positive post-therapy result the risk was even higher, 4.6 times that of patients with a negative post-therapy FISH result. Positive post-therapy FISH results were also associated with a 9.4-fold higher risk for progression to muscle invasive disease, the team found. Two of 9 patients whose FISH results went from negative pre-therapy to positive post-therapy developed muscle invasive tumors, as did three-quarters of the patients with positive FISH results both pre- and post-therapy. “One of the most significant things to come out of this work is the finding that BCG does not cause false positive FISH results,” Dr. Halling commented. “Consequently, FISH can be used to reliably determine if a patient treated with BCG has failed therapy. This is an important advance, since the inflammatory changes caused by BCG make it difficult to interpret cystoscopy and cytology findings.” He added, “It is my hope that new laboratory techniques such as FISH will enable urologists to better manage their patients with urothelial carcinoma (UC) and that this will eventually lead to a reduction in UC mortality.”(Source: J Urol 2005;173:401-404: Reuters Health: Will Boggs, MD: Oncolink: February 2005.)