Microsatellite instability in transitional cell carcinoma of the urinary tract and its relationship to clinicopathological variables and smoking.

To determine whether microsatellite instability is involved in the development of transitional cell carcinoma (TCC) of the urinary tract, a microsatellite instability assay was carried out using PCR with 9 microsatellite loci. Thirty-eight TCC samples (30 patients with bladder cancer, 5 with renal pelvic tumors and 3 with ureteral tumors) and 1 lymph node with metastasis were examined. Microsatellite instability was found in 8 of 38 tumors examined, and 3 showed alterations in more than 2 microsatellite loci. All 8 tumors were beyond grade 2 and stage pT2 advanced tumors. Stages pT1-2 and pT3-4 patients differed significantly. Microsatellite instability was greater in smokers than non-smokers, but the differences were not significant. Microsatellite instability in TCC of the urinary tract is rare in superficial tumors but more common in invasive tumors. Microsatellite alterations would thus appear to occur, and possibly be importantly involved, in the tumorigenesis of urinary tract TCC.