Prevalence and spectrum of microsatellite alterations in nonmuscle invasive bladder cancers

We aimed to identify interesting deleted chromosomal regions for bladder cancer diagnosis and carcinogenesis, and to evaluate the association between loss of heterozygosity (LOH) and clinico-pathological parameters. Microsatellite analysis was performed on urine sediment and tumor tissue from 43 consecutive patients with superficial transitional cell carcinoma (TCC) and from 42 consecutive controls. Informative cases were scored as LOH or allelic loss (AL) according to the decrease of the allelic-imbalance ratio. The prevalence of LOH and AL was 39.5% and 86%, respectively. Chromosome 9 was the most frequently altered, especially at 9p (35%). The total number of microsatellite alterations per analysis was correlated with age, grade, stade and EAU classification. The locus 17p13.1 was strongly associated with high-stage (p=0.01) and high-grade tumors (p=0.02). Specificity and sensitivity of LOH was 100% and 39.3% for diagnosis of malignant urinary disease. Specificity and sensitivity of AL was 73.8% and 88%, respectively. Allelic losses are a frequent and early event in bladder cancer, especially at 9p. Thanks to its high specificity, LOH may serve as a complementary tool for non invasive diagnosis of bladder cancer. Further study is warranted to evaluate the prognostic value of LOH on recurrence, progression and muscle invasion.