Human Papillomavirus Infection And P16Protein Expression In Oropharyngeal Squamous Cell Carcinoma And Their Clinical Significance

[Background]More and more studies have shown an etiologic role of infection with human papillomavirus (HPV) in a subset of oropharyngeal squamous cell carcinomas (OSCC) without exposure to cigrettes and alcohol. High-risk HPV has been established an important etiologic factor in a subset of OSCC and play a role in carcinogenesis. HPV-positive tumors show an improved response rate to chemo/radiotherapy compared to HPV negative OSCC,and have improved survival outcomes. Many studies about the relationship between HPV and OSCC have been derived from western countries,but none from China mainland.[Objectives] In this study,we will retrospectively evaluate a series of66patients with OSCC treated at CAMS.We will investigate the infection rate and subtypes of human papillomavirus and detect p16protein expression.We are aimed to assess the differences in patient characteristics and survival between different HPV and p16protein ststus,determine whether HPV and p16protein ststus is of prognostic importance in OSCC,and further understand the carcinogenesis of HPV-related OSCC.[Methods] Formalin-fixed,paraffin-embedded tissue blocks of66patients who met the eligibility criteria were obtained from patients diagnosed with oropharyngeal squamous cell carcinomas treated in Cancer Hospital of Chinese Academy of Medical Sciences.A "sandwich" technique was used to cut paraffin sections for for HPV-DNA analysis. HPV-DNA was detected using the SPF10LiPA25version1assay.p16protein expression was evaluated by immunohistochemistry.The clinicopathologic features of patients with different HPV-DNA and p16protein status were analyzed.Patients were retrospectively followed up.The primary end point was overall survival(OS) and disease spesific survival(DSS).SPSS17.0software was used for statistical analysis.Survival data were analyzed by means of the Kaplan-Meier method,and survival curves were compared with the log-rank test in univariate analysis.Cox regression model was used for multivariate analysis.[Results] HPV-DNA was detected in11(16.7%) of all specimens. Among them.7were type HPV-16,and other types include HPV-16/11,HPV-35,HPV-58/52,and HPV-33/52/54for each.HPV-16was detected in72.73%of all the virus postive specimens. There were more females in HPV-positive tumors than HPV-negative tumors(36.4%and1.8%,respectively,P=0.002).Patients with HPV-positive tumors were more likely to be non-smokers (36.4%vs O,respectively)and non-drinkers(45.5%vs1.8%,respectively) than HPV negative tumors,with statistically significant difference(P=0.001and0.001,respectively).Based on Kaplan-Meier estimates,both overall survival(OS) and disease specific survival(DSS) for patients with HPV-positive tumors improved significantly compared with that of patients with HPV-negative tumors(/*=0.016and0.030,log-rank test).The estimated3-year OS and DSS were90.0%and90.0%respectively,among HPV-positive patients.By contrasts-year OS and DSS among HPV-negative patients were52.4%and56.4%.Patients with HPV-positive tumors had a89%reduction in risk of death from cancer when compared with HPV-negative HNSCC patients (HR=0.106;95%CI=0.014-0.787).p16protein expression was detected in9of the11patients with HPV positive tumors(81.8%),and only16patients of55HPV negative tumors(29.1%).The p16protein expression was highly correlated with the presence of HPV-DNA(P=0.002).Univariate analysis of the5-year OS and DSS revealed a significantly better outcome for patients with p16protein-positive tumors than p16protein-negative tumors (P=0.000and0.001)3year OS and DSS were89.6%and43%,89.6%and47.1%, respectively.And patients with p16protein-positive tumors also showed a reduction of locoregional recurrence than p16protein-negative tumors (P=0.004).Tumors were classified into three classes on the basis of p16protein and HPV-DNA status: group I, HPV(+), p16protein(+);group Ⅱ, HPV-DNA(+)/pl6protein(-) or HPV-DNA(-)/p16protein(+); and group Ⅲ, HPV-DNA(-)/p16protein(-).OS and DSS were reduced significantly in group III (42%and46.4%) compared with the other two groups(100%and77.8%,100%and77.8%,P＝0.001and0.004, respectively). When multivariable analysis was performed,patients with p16protein-negative tumors had a higher risk of death than patients with p16protein-positive tumors(HR0.114,95%CI0.033-0.390,P＝0.001).. [Conclusions] HPV infection rate of OSCC in this study was16.7%.HPV subtypes and the clinicopathological features of HPV-positive OSCCs are in accordance with thoses from western literatures.Patients with HPV-positive OSCCs have significantly reduced recurrence and death risk,and better prognosis than patients with HPV-negative tumors.HPV infection is an independent prognostic factor.The p16protein expression was highly correlated with the presence of HPV-DNA,and might be a surrogate marker for HPV-positive OSCC.pl6protein expression is a reliable prognostic indicator for OSCC, and it's prognostic value for survival is fully equivalent to HPV status.Combination of p16protein and HPV status will helps to more accurately stratify oropharyngeal carcinoma.