Detection of c-erbB-2 amplification in transitional cell bladder carcinoma using competitive PCR technique

Purpose: We used competitive PCR to verify retrospectively the prognostic significance of c-erbB-2 oncogene amplification in transitional cell bladder carcinomas as a predictive index of patient survival with a maximum follow-up of nine years, and to investigate the variations of c-erbB-2 amplification during bladder carcinoma recurrence and/or progression from superficial to more invasive states. Materials and Methods: Oncogene amplification was determined by an accurate and sensitive procedure based on competitive PCR. Measurements were performed in DNA extracted from fresh cancers or from formalin-fixed, paraffin-embedded tumor samples. Results: The overall mean incidence of c-erbB-2 oncogene amplification was 26% (24/92), with a significant relationship with tumor grade (p<0.0001). We did not find any statistical difference in survival probability between subjects with (20%) or without (30%) oncogene amplification. During tumor progression we observed a limited increase of tumors carrying oncogene amplification (2 of 20) whereas the mean degree of amplification was not affected, Conclusions: c-erbB-2 amplification seems to be a genetic event related to the degree of bladder tumor differentiation. However the presence and/or the degree of this genetic alteration do not seem predictive of tumor progression, recurrence and survival probability, at least in patients with advanced transitional cell bladder carcinoma. These data seem to indicate that the amplification of c-erbB-2 in bladder carcinoma could be considered as an epiphenomenon, present in a subset of tumors but apparently not related to the clinical outcome.