Therefore, the role of HPV in bladder PLX3397 cell line carcinoma has still not been consensual. Several explanations for this variability of HPV prevalence in bladder carcinoma have been proposed, including sampling problems, contamination, differences in sensitivity of the detection methods used, and differences among study populations and histological tumor type. The mean sample size in the previous reports was 60 (ranging from 10 to 187), and large population studies, including more than 100 subjects, are limited. Further, there have also been limited studies, including usage of the high-sensitivity PCR method, which can detect a wide spectrum of HPV types.

Thus, it is important to investigate a sufficient number of cases by using a standardized microbiological technique to reach more definite conclusions. Nineteen previous studies compared HPV-positive rate between bladder carcinoma and non-carcinomatous lesions, such as non-specific cystitis and normal mucosa (Table 2), and the prevalence of HPV varied on the basis of sampling, processing method, or geographic location see more of study population. Thirteen (68%) studies demonstrated that the HPV prevalence (12–81%) in bladder carcinoma was significantly higher compared with that (0–33%) in non-carcinomatous bladder mucosa, and have supported the etiological role of HPV in the development of

bladder carcinoma. Many of recent case–control studies are especially likely to suggest a possible correlation with HPV carcinogenesis by using the high-sensitivity PCR method. One previous case–control study reported that HPV-DNA was detected

in 18 of 117 (15%) bladder carcinomas and this finding was supported by the presence of HPV-DNA signals by ISH analysis in HPV-positive samples [69]. Alternatively, Cai et al. described that high-risk HPV-DNA in bladder carcinoma was detected in 27 of 78 (34.6%) samples, and was also detected in 36 of 78 (46.1%) urine samples obtained from the patients with bladder carcinoma [70]. Conversely, HPV was detected in six of 59 (10.1%) specimens from patients without cancer, and this study highlights the correlation between urothelial bladder carcinoma and high-risk type HPV infection, suggesting the potential C-X-C chemokine receptor type 7 (CXCR-7) pathogenetic role of high-risk HPV types in urothelial bladder carcinoma development [70]. A recent meta-analysis with 19 case–control studies reported an HPV prevalence of 16.88% (95% CI, 15.53%–18.31%) among the bladder carcinoma cases, most of which were high-risk HPV types, and suggested that infection with high-risk HPV types, especially HPV type 16, may play a role in bladder carcinogenesis [76]. Another meta-analysis, including 21 studies, also found a significant effect between HPV and bladder carcinoma with an odds ratio (OR) of 2.13 (95% CI, 1.54%–2.95%) [77]. HPV infection is likely to have a certain etiological correlation with bladder carcinoma.