Background: Oropharyngeal squamous cell carcinomas (OPSCCs) are traditionally caused by smoking and excessive alcohol consumption. However, in the last decades high-risk human papillomavirus (HPV) infections play an increasingly important role in tumorigenesis. HPV-driven OPSCCs are known to have a more favorable prognosis, which has led to important and marked changes in the recently released TNM-8. In this 8th edition, OPSCCs are divided based on p16 immunostaining, with p16 overexpression as surrogate marker for the presence of HPV. The aims of this study are to evaluate TNM-8 on a Dutch consecutive cohort of patients with p16-positive OPSCC and to determine the relevance of additional HPV DNA testing. Patients and methods: All OPSCC patients without distant metastases at diagnosis and treated with curative intent at VU University Medical Center (2000-2015) and Erasmus Medical Center (2000-2006) were included (N=1204). HPV status was determined by p16 immunostaining followed by HPV DNA PCR on the p16-immunopositive cases. We compared TNM-7 and TNM-8 using the Harrell's C index. Results: In total, 388 of 1204 (32.2%) patients were p16-immunopositive. In these patients, TNM-8 had a markedly better predictive prognostic power than TNM-7 (Harrell's C index 0.63 versus 0.53). Of the 388 p16-positive OPSCCs, 48 tumors (12.4%) were HPV DNA-negative. This subgroup had distinct demographic, clinical and morphologic characteristics and showed a significantly worse five-year overall survival compared with the HPV DNA-positive tumors (P < 0.001). Conclusions: TNM-8 has a better predictive prognostic power than TNM-7 in patients with p16-positive OPSCC. However, within p16-positive OPSCCs, there is an HPV DNA-negative subgroup with distinct features and a worse overall survival, indicating the importance to perform additional HPV DNA testing when predicting prognosis and particularly for selecting patients for de-intensified treatment regimens.

Additional Metadata
Keywords HPV DNA test, Oropharyngeal squamous cell carcinoma, Outcome prediction, P16 immunohistochemistry, TNM classification
Persistent URL dx.doi.org/10.1093/annonc/mdy060, hdl.handle.net/1765/113127
Journal Annals of Oncology
Grant This work was funded by the European Commission 7th Framework Programme; grant id h2020/689715 - Big Data and models for personalized Head and Neck Cancer Decision support (BD2Decide)
Citation
Nauta, I.H. (I. H.), Rietbergen, M.M. (M. M.), van Bokhoven, A.A.J.D. (A. A.J.D.), Bloemena, E, Witte, B.I, Heideman, D.A.M, … Leemans, C.R. (2018). Evaluation of the eighth TNM classification on p16-positive oropharyngeal squamous cell carcinomas in the Netherlands and the importance of additional HPV DNA testing. Annals of Oncology, 29(5), 1273–1279. doi:10.1093/annonc/mdy060