Different prognostic models for different patient populations: validation of a new prognostic model for patients with oropharyngeal cancer in Western Europe

Objective: The presence of human papillomavirus (HPV) infection in oropharyngeal squamous cell carcinoma (OPSCC) is a major determinant in prognostic risk modelling. Recently, a prognostic model was proposed in which HPV status, comorbidity and nodal stage were the most important prognostic factors to determine high-, intermediate-and low-risk survival groups. Here, we report on the validation of this model using an independent single-institutional cohort. Methods: A total number of 235 patients curatively treated for OPSCC in the period 2000-2011 at the MUMC (Maastricht University Medical Center, The Netherlands) were included. The presence of an oncogenic HPV infection was determined by p16 immunostaining, followed by a high-risk HPV DNA PCR on the p16-positive cases. The model variables included were HPV status, comorbidity and nodal stage. As a measure of model performance, the Harrell's Concordance index (Harrell's C-index) was used. Results: The 5-year overall survival (OS) estimates were 84.6%, 54.5% and 28.7% in the low-, intermediate-and high-risk group, respectively. The difference between the survival curves was highly significant (P