Relationship between HPV infection/p16 expression and radiotherapy prognosis in oropharyngeal squamous cell carcinoma

Objective: To investigate the relationship between human papillomavirus (HPV) infection/p16 expression and radiotherapy prognosis in oropharyngeal squamous cell carcinoma (OSCC) and the prognostic value of p16 in OSCC patients treated with radiotherapy. Methods: Tissue samples were collected from 42 patients newly diagnosed with OSCC in our hospital from January 1999 to December 2008. PCR was performed to detect HPV DNA, and p16 expression was measured by immunohistochemistry. The chi-square test was used to compare the local/regional control rate (CR) between HPV (+)/p16 (+) patients and HPV (-)/p16 (-) patients after radical radiotherapy and evaluate the association between HPV infection and p16 expression; the Kaplan-Meier method was used to calculate overall survival (OS), and the log-rank test was used for survival difference analysis. Results: The follow-up rate was 100%.The HPV infection rate was 19%, and the positive rate of p16 was 43%. In patients who received radical radiotherapy, the local CR for HPV (+) patients was 100%, versus 54% for HPV (-) patients (P =0.026); the local CR for p16 (+) patients was 92%, versus 44% for p16 (-) patients (P=0.006); the locoregional CR for p16(-) patients was 69%, versus 22% for p16 (-) patients (P=0.009). For high-risk patients, HPV infection was significantly associated with p16 expression (P=0.000). The 3-year OS rates for p16 (+) and p16 (-) patients were 91% and 2 6 %, respectively (P=0.001). Conclusions: The p16 expression is closely associated with HPV infection in OSCC patients, and it is expected to become one of the prognostic markers in OSCC patients treated with radiotherapy. (authors)