BERKELEY, CA (UroToday.com) - Adjuvant intravesical therapy with BCG is commonly used to decrease the probability of recurrence and progression in patients with bladder tumors. While this therapy works in a fair proportion of patients, there are those who recur and even progress onto muscle-invasive stages. It is crucial that we identify means of differentiating potential 'responders' from 'non-responders' so that we might offer them alternative therapy (including cystectomy) prior to disease progression.

In the March issue of European Urology, Mengual and colleagues suggest that the multiprobe fluorescent in situ hybridization (FISH) assay (known as Urovysion® in the US) might be useful for determining the response of patients to BCG. Of 65 patients enrolled in the study, 85% demonstrated a positive FISH pre-BCG (i.e. after resection). When FISH was performed on bladder washing after the last of 6 weeks of BCG instillation (at an average of 2.9 mos, range 2 to 6 months after BCG), 45% had a positive post-BCG FISH result. If a patient with a positive pre-BCG FISH remained positive post-BCG, his or her likelihood of developing a recurrence was 2.96 times that of someone who converted to a negative post-BCG FISH (48% versus 23%, p = 0.02).

The results presented in this study support the use of FISH as a surveillance modality but the authors claim that it is useful in risk-stratification of patients treated with BCG. It is not surprising that patients with persistent disease (positive pre and post BCG FISH) should be at higher risk of recurrence, as was demonstrated by Kipp et al (Journal of Urology, 2005). What is surprising, however, is that if a patient converted from a negative pre-BCG FISH to a positive post-BCG FISH, this did not significantly alter the risk of recurrence (p=0.61). Furthermore, the pre-BCG FISH status was not a predictor of either disease recurrence or progression, which contrasts with prior reports. Notably too, there were nine false negative post-BCG FISH results and fourteen false positive post-BCG results (which might be an artifact of the short duration of follow-up of patients with a mean of 15.9 months (median not reported).

Thus, until more conclusive data (with longer follow-up) are available, the use of FISH after BCG therapy can be supported as a surveillance modality, but treatment decisions should not be based on findings from this one test alone.

Mengual L, Marín-Aguilera M, Ribal MJ, Burset M, Villavicencio H, Oliver A, Alcaraz A

Eur Urol; Mar 13, 2007
DOI: 10.1016/j.eururo.2007.03.001

UroToday.com Bladder Cancer Section

Written by Ashish M. Kamat, a Contributing Editor with UroToday.

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