Progression from superficial to invasive carcinoma of the bladder: genetic evidence of either clonal heterogeneous events.

Until now, no definitive molecular evidence proving or disproving a true progression from superficial to invasive bladder tumors has been reported. A total of 36 lesions from 6 patients affected by invasive bladder cancer after multiple superficial recurrences were analyzed for loss of heterozygosity on 8 loci of chromosome 9 and 2 loci of chromosome 17. In addition, the clonal composition of the tumors from two female patients was examined using the human androgen receptor assay. Our data suggest that papillary bladder lesions can and sometimes do make a true progression into invasive life-threatening tumors; however, this progression is not an invariable sequence because it was definitely proven in 2 but not confirmed in 3 of the cases we examined.