FIG. 21:  Reflex testing is an interesting possibility in patients with atypia.  Two prospective studies^[12,13] have shown that a positive UroVysion® FISH assay result in the setting of atypical cystoscopy or atypical cytology indicates a significant risk for the presence of cancer.  In patients with a history of cancer and atypical cystoscopy and a positive FISH assay, >60% were shown to have cancer.^[12]  In cases with atypical cytology and a positive FISH assay, more than 40% had cancer.  Even in patients without history of cancer, there was a high positive predictive value. 

A second study^[13] validated these findings, with a very high positive predictive value for high-grade cancers in patients with atypical cystoscopy and a positive FISH result.  The negative predictive value was also quite high, so the cancer was less likely to be missed when the FISH assay was negative. 

Based on the results of these studies, the guidelines now suggest that this is a possible use for patients with positive FISH assay in the setting of atypical cystoscopy or cytology.