Detection of human papillomavirus infection and p16 immunohistochemistry expression in bladder cancer with squamous differentiation

To determine the potential association between HPV infection and the squamous cell component of urothelial carcinoma (UC) of the bladder and to validate p16 overexpression as a surrogate marker for HPV infection in these cancers among Koreans. We analyzed the presence of HPV infection using an HPV-DNA chip and the expression of p16 using immunohistochemistry in 47 subjects between July 2001 and March 2011. The study group (n = 35) included patients with squamous differentiation of UC of the bladder. The control group (n = 12) included patients with squamous metaplasia of the bladder. Baseline characteristics of control and study groups were similar. HPV DNA detection rates were approximately 2-fold higher in the study than the control group (17.1% [6/35] versus 8.3% [1/12], respectively), but the difference was not statistically significant. P16 overexpression was detected in 16/35 (45.7%) study group and 1/12 (8.3%) control group samples (p = 0.034). Both HPV-positivity and p16 overexpression were present in 3/35 (8.8%) study group samples, but none of the control group (p = 0.295). In the study group, the percentage of HPV-positive cases who were non-smokers was 2-fold higher than the percentage of HPV-negative cases who were non-smokers (66.7% [4/6] versus 31.0% [9/29], respectively); however, statistical significance was not achieved due to the small sample size. HPV infection may be associated with UC of the bladder with squamous differentiation, especially in non-smokers. However, p16 expression does not appear to be a strong surrogate marker for evidence of HPV infection in this type of cancer.