AIM: The biological behaviour of superficial type transitional carcinomas of the urinary bladder can not be predicted. To try to differentiate those tumors that will present aggressive behaviour with infiltrative recurrences from those that will not, we studied, at the mRNA level, the expression of two membrane proteins, EGFr and c-erbB2, and of k-ras oncogene. METHODS: The mRNAs relative quantitation as performed, after RT-PCR, from histological sections cut from formalin-fixed and paraffin-embedded tissues. Twenty-three patients with urinary bladder transitional carcinoma have been studied for EGF-receptor, c-erbB2 and k-ras oncogene. The expression has been correlated with the outcomes of the follow-up period (infiltrative or superficial recurrences). RESULTS: The mRNA or EGFr was in average more expressed in tumors that continue to be superficial in the relapses, but for c-erbB2 the level of mRNA was similar in both, the more and less aggressive groups. The expression of k-ras was higher in cases associated with more infiltrative tumor relapses. CONCLUSIONS: In this preliminary study we did not identify any specific marker that can clearly predict the prognosis of superficial type transitional carcinoma of the urinary bladder; only k-ras expression is connected in some cases with the aggressiveness of the tumors. The expression of EGFr gave us intriguing results, it is in fact higher in the superficial carcinomas that do not tend to become infiltrative of the urinary bladder wall
