A comprehensive evaluation of human papillomavirus positive status and p16INK4a overexpression as a prognostic biomarker in head and neck squamous cell carcinoma.

Abstract

Head and neck squamous cell carcinoma (HNSCC) patients with human papillomavirus (HPV) infection have better prognosis than those without HPV infection. Although p16INK4a expression is used as a surrogate marker for HPV infection, there is controversy as to whether p16INK4a reliably indicates HPV infection. Here, to evaluate the accuracy of p16INK4a expression for determining HPV infection and the prognostic value of HPV infection and p16INK4a expression for HNSCC survival, especially oropharyngeal squamous cell carcinoma (OPSCC) survival, 150 fresh-frozen HNSCC samples were analyzed for HPV DNA, E6/E7 mRNA and p16INK4a expression by polymerase chain reaction and immunohistochemistry. p16INK4a expression was scored from 0 to 4 according to the percentage of p16INK4a-positive cells, with overexpression defined as >40% positive cells. Of the 150 tumor samples tested, 10 tumors were nasopharyngeal, 53 oropharyngeal, 39 hypopharyngeal, 24 laryngeal and 24 were located in the oral cavity. HPV DNA was detected in 47 (31.3%) samples, but only 21 also exhibited HPV mRNA expression. Inter-rater agreement was low between p16INK4a expression and HPV DNA presence and between p16INK4a expression and HPV mRNA expression, but was good between the combination of HPV DNA status and p16INK4a overexpression and HPV mRNA expression. Three-year recurrence-free survival was significantly higher for OPSCC patients who were HPV DNA-positive than for OPSCC patients who were HPV DNA-negative (P=0.008) and for OPSCC patients over-expressing p16INK4a than for without overexpressing p16INK4a (P=0.034). Multivariate analysis revealed that T1-3 stage and the combination of HPV DNA positivity and p16INK4a overexpression predicted significantly better recurrence-free survival. This combination is a more accurate marker for active HPV infection in HNSCC than HPV DNA status or general p16INK4a-positive status alone and offers a useful and reliable method for detecting and determining the prognosis of HPV-related HNSCC.