Microsatellite alterations in superficial and locally advanced transitional cell carcinoma of the bladder

Recent studies described the existence of genetic instability associated wi th bladder carcinogenesis. Alterations at microsatellite loci constitute a recognized tumor marker of genome instability. A series of 21 transitional cell carcinomas of the bladder (10 superficial and 11 invasive carcinomas) was analyzed for the presence of alteration in 12 microsatellite loci, in o rder to detect the role of microsatellite instability in genesis and progre ssion of human bladder cancer. Our preliminary results indicate 3 trend to presence of microsatellite instability (MI) in invasive and undifferentiate d tumors compared to superficial and differentiated forms. Eight out of 11 T2-T4 tumors presented a number of altered microsatellite greater than or e qual to 2 compared to one out of 10 Ta-T1 bladder carcinomas (p=0.008). Mor eover, 9 out of 15 (60%) G2-G3 tumors had significantly more unstable micro satellites than those differentiated (0 out of 6) (p=0.019). Our results pr ovide an insight into the potential usefulness of microsatellite analysis o f bladder carcinoma to better understand which neoplastic forms will evolve to invasive progression and indicate that pronounced MI may be associated with more aggressive bladder carcinomas.