Clinical value of vesical leukoplakia and evaluation of the neoplastic risk by mutation analyses of the tumor suppressor gene TP53

Aim: Leukoplakia has been found to be precancerous in organs covered with squamous epithelium. The present study was conducted to determine whether leukoplakia described in the female bladder is also a premalignant lesion. Methods: Between 1973 and 1996, 77 female patients were diagnosed with vesical leukoplakia by cystoscopy and cytology and were followed-up until 2004 (mean follow-up time: 8.3 years). A survey was conducted to analyze exposure to cocarcinogens. Additionally, DNA was isolated from 36 urine sediments and analyzed for TP53 mutations. The results were compared to the mutation frequency of TP53 in urine sediments from patients diagnosed with transitional cell carcinoma (TCC) of the bladder and healthy controls. Results: The whitish lesion was mostly located at the trigone and varied in size and location during the follow-up years. TP53 mutations were detected in 6 out of 36 urine samples in exons 5, 6 and 7 (mutation frequency: 16.7%). Among control patients with no leukoplakia or TCC of the bladder (n = 70), the spontaneous mutation frequency was similar (14.3%). In contrast, the mutation frequency in patients with TCC of the bladder (n = 148) revealed 39.9% in exons 5, 6, 7 and 8. The present study did not show any statistically significant correlations between chronic inflammations, TP53 mutations, exposure to carcinogens and vesical leukoplakia. Conclusions: Our data suggest that vesical leukoplakia does not necessarily hold neoplastic potential and needs to be clearly distinguished from leukoplakia in other localizations. Therefore, we suggest that a biopsy can be omitted, if follow-up controls by cystoscopy are performed regularly.