Urinary human polyomavirus and papillomavirus infection and bladder cancer risk

Background: The association of transitional cell carcinomas of the bladder (TCB) with Schistosoma haematobium suggested a possible role of infections in the aetiology of TCB. Methods: In all, 114 TCB cases and 140 hospital controls from Pordenone Province were enrolled within an Italian multi-centric case-control study. Urine samples were screened for DNA from five human polyomaviruses (HPyV) (JCV, BKV, MCV, WUV, and KIV); SV40; and 22 mucosal human papillomaviruses (HPV) using highly sensitive PCR assays. Odds ratios (ORs) and corresponding confidence intervals (CIs) were computed for risk of TCB by HPyV-or HPV-positivity using unconditional logistic regression. Results: Human polyomavirus prevalence was similar in TCB cases (71.7%) and controls (77.7%) (OR for TCB=0.85; 95% CI: 0.45-1.61). JCV was the most frequently detected HPyV type. No individual HPyV showed a significant association. Among cases, HPyV-positivity was not associated with tumour characteristics, but it was significantly lower in women than men and among current and former smokers than never smokers. Human papillomavirus was detected in seven cases and five controls (OR=1.52; 95% CI: 0.42-5.45). Conclusion: The present small study does not support an involvement of HPyV or HPV infection in TCB aetiology in immunocompetent individuals. Differences in HPyV-positivity by sex and smoking may derive from differences in either acquisition or persistence of the infection.