Human papillomavirus type 16 (HPV16) plays a role in the development of a subgroup of head and neck squamous cell carcinomas (HNSCC). However, uncertainty exists about the true impact of HPV in this tumor type as conflicting reports have been published with prevalence rates from 0 to 100%. We aimed to find a detection algorithm of a biologically and thus clinically meaningful infection, applicable for high‐throughput screening of frozen and formalin‐fixed paraffin embedded (FFPE) specimens. By considering detection of HPV E6 oncogene expression in frozen biopsies as gold standard for a meaningful HPV infection, the value of several assays was evaluated on FFPE tumor specimens and sera of 48 HNSCC patients. The following assays were evaluated on FFPE tissue samples: HPV DNA general primer (GP)5+/6+ PCR, viral load analysis, HPV16 DNA FISH detection, HPV16 E6 mRNA RT‐PCR, p16 immunostaining, and on corresponding serum samples detection of antibodies against the HPV16 proteins L1, E6 and E7. Comparing single assays on FFPE tissue samples detection of E6 expression by RT‐PCR was superior, but application remains at present limited to HPV16 detection. Most suitable algorithm with 100% sensitivity and specificity appeared p16 immunostaining followed by GP5+/6+ PCR on the p16‐positive cases. We show that clinically meaningful viral HPV infections can be more reliably measured in FFPE HNSCC samples in a standard and high throughput manner, paving the way for prognostic and experimental vaccination studies, regarding not only HNSCC, but possibly also cancer types with HPV involvement in subgroups such as penile and anal cancer.

Human papillomavirus (HPV) infection has been etiologically linked to oropharyngeal squamous cell carcinoma (OPSCC). The prevalence of HPV‐positive OPSCC varies between studies, ranging from 20 to 90%. This may be related to the lack of a standardized HPV detection assay as well as to the time period in which HPV prevalence is investigated, as rising incidence rates are reported over the last decades. Here, we validated our previously defined test algorithm for HPV detection in formalin‐fixed paraffin‐embedded (FFPE) tumor specimen consisting of p16^INK4A immunostaining followed by high‐risk HPV DNA detection by GP5+/6+ PCR on the positive cases (Smeets et al., Int J Cancer 2007;121:2465–72). In addition, we analyzed HPV prevalence rates in OPSCCs in the years 1990–2010. The test algorithm was validated on a consecutive series of 86 OPSCCs collected during 2008–2011, of which both fresh frozen and FFPE samples were available. We performed HPV‐E6 RT‐PCR on the frozen samples as gold standard and applied the algorithm to the corresponding FFPE samples. The test algorithm showed an accuracy of 98%. Using the validated algorithm, we determined the presence of an oncogenic HPV infection in 240 OPSCCs of patients diagnosed in the years 1990–2010 at our center. A significant increase in the proportion of HPV‐positive samples was observed, from 5.1% in 1990 to 29.0% in 2010 (p = 0.001). In conclusion, we confirmed the accuracy of the test algorithm for HPV detection in FFPE tumor specimen and we found a significant increase in the prevalence of HPV in OPSCC over the last two decades at our center.

The presence of human papillomavirus (HPV)-infection in oropharyngeal squamous cell carcinoma (OPSCC) is a major determinant in prognostic risk modeling. However, most risk models are based on clinical trials which only include a selected patient population. The clinical significance of HPV and other prognostic factors in patients with OPSCC remains to be evaluated in a large, unselected cohort, which also includes patients with stage I/II disease and patients with severe comorbidity. All patients diagnosed with OPSCC in 2000–2006 in two Dutch university hospitals were included. The presence of an oncogenic HPV infection was determined by p16-immunostaining, followed by a high-risk HPV general primer 5+/6+ DNA PCR on the p16-positive cases. Cox regression analysis was carried out to compare survival rates between HPV-positive and HPV-negative patients and a prognostic model was generated by recursive partitioning. In total, 163 of 841 (19.4%) tumors were HPV-positive. Patients with HPV-positive OPSCC had a more favorable overall survival [73.5% versus 40.9% after 5 years; P < 0.001; hazard ratio = 0.34, 95% confidence interval (CI) 0.25–0.48] compared with patients with HPV-negative OPSCC. Patients with p16-positive but HPV DNA-negative tumors showed a significantly less favorable survival than patients with p16-positive and HPV DNA-positive tumors (P < 0.001). A prognostic model was developed in which patients were classified into three risk groups according to HPV status, nodal stage and comorbidity. [Harrell's concordance index of 0.68 (95% CI 0.65–0.71)]. Tumor HPV status is a strong and independent prognostic factor for survival among patients with OPSCC. A prognostic risk model was proposed, based on our large, unselected cohort of patients with HPV status, comorbidity and nodal stage being the important prognostic factors. In addition, this study emphasizes the importance of performing an HPV DNA-specific test besides p16-immunostaining.

Oropharyngeal squamous cell carcinomas (OPSCCs) are traditionally caused by smoking and excessive alcohol consumption. However, in the last decades high-risk human papillomavirus (HR-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 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. 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 = 1,204). HPV-status was established 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. In total, 388 of 1,204 (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 to the HPV DNA-positive tumors (P < 0.001). 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.