BACKGROUND
p16INK4a (p16) immunohistochemistry is the most widely used biomarker assay for inferring HPV causation in oropharyngeal cancer in clinical and trial settings. However, discordance exists between p16 and HPV DNA or RNA status in some patients with oropharyngeal cancer. We aimed to clearly quantify the extent of discordance, and its prognostic implications.
METHODS
In this multicentre, multinational individual patient data analysis, we did a literature search in PubMed and Cochrane database for systematic reviews and original studies published in English between Jan 1, 1970, and Sept 30, 2022. We included retrospective series and prospective cohorts of consecutively recruited patients previously analysed in individual studies with minimum cohort size of 100 patients with primary squamous cell carcinoma of the oropharynx. Patient inclusion criteria were diagnosis with a primary squamous cell carcinoma of oropharyngeal cancer; data on p16 immunohistochemistry and on HPV testing; information on age, sex, tobacco, and alcohol use; staging by TNM 7th edition; information on treatments received; and data on clinical outcomes and follow-up (date of last follow-up if alive, date of recurrence or metastasis, and date and cause of death). There were no limits on age or performance status. The primary outcomes were the proportion of patients of the overall cohort who showed the different p16 and HPV result combinations, as well as 5-year overall survival and 5-year disease-free survival. Patients with recurrent or metastatic disease or who were treated palliatively were excluded from overall survival and disease-free survival analyses. Multivariable analysis models were used to calculate adjusted hazard ratios (aHR) for different p16 and HPV testing methods for overall survival, adjusted for prespecified confounding factors.
FINDINGS
Our search returned 13 eligible studies that provided individual data for 13 cohorts of patients with oropharyngeal cancer from the UK, Canada, Denmark, Sweden, France, Germany, the Netherlands, Switzerland, and Spain. 7895 patients with oropharyngeal cancer were assessed for eligibility. 241 were excluded before analysis, and 7654 were eligible for p16 and HPV analysis. 5714 (74·7%) of 7654 patients were male and 1940 (25·3%) were female. Ethnicity data were not reported. 3805 patients were p16-positive, 415 (10·9%) of whom were HPV-negative. This proportion differed significantly by geographical region and was highest in the areas with lowest HPV-attributable fractions (r=–0·744, p=0·0035). The proportion of patients with p16+/HPV– oropharyngeal cancer was highest in subsites outside the tonsil and base of tongue (29·7% vs 9·0%, p<0·0001). 5-year overall survival was 81·1% (95% CI 79·5–82·7) for p16+/HPV+, 40·4% (38·6–42·4) for p16–/HPV–, 53·2% (46·6–60·8) for p16–/HPV+, and 54·7% (49·2–60·9) for p16+/HPV–. 5-year disease-free survival was 84·3% (95% CI 82·9–85·7) for p16+/HPV+, 60·8% (58·8–62·9) for p16–/HPV–; 71·1% (64·7–78·2) for p16–/HPV+, and 67·9% (62·5–73·7) for p16+/HPV–. Results were similar across all European sub-regions, but there were insufficient numbers of discordant patients from North America to draw conclusions in this cohort.
INTERPRETATION
Patients with discordant oropharyngeal cancer (p16–/HPV+ or p16+/HPV–) had a significantly worse prognosis than patients with p16+/HPV+ oropharyngeal cancer, and a significantly better prognosis than patients with p16–/HPV– oropharyngeal cancer. Along with routine p16 immunohistochemistry, HPV testing should be mandated for clinical trials for all patients (or at least following a positive p16 test), and is recommended where HPV status might influence patient care, especially in areas with low HPV-attributable fractions.
Author Affiliations
1Institute of Head and Neck Studies and Education (InHANSE), Institute of Cancer and Genomics Sciences, University of Birmingham, Birmingham, UK;2Department of Medical Oncology, Catalan Institute of Oncology (ICO), Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L’Hospitalet de Llobregat, Barcelona, Spain;3Cancer Epidemiology Research Programme, Catalan Institute of Oncology (ICO), Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L’Hospitalet de Llobregat, Barcelona, Spain;4Department of Medicine, University of Barcelona, Barcelona, Spain;5Department of Otolaryngology, Head and Neck Surgery and Audiology, Copenhagen University Hospital—Rigshospitalet, Copenhagen, Denmark;6Epidemiology and Public Health, Centro de Investigación Biomédica en Red: Epidemiología y Salud Pública (CIBERESP), Instituto de Salud Carlos III, Madrid, Spain;7Department of Otolaryngology, Head and Neck Surgery, Erasmus MC Cancer Centre, Rotterdam, Netherlands;8Department of Otorhinolaryngology, Head and Neck Surgery, Medical Faculty, University of Cologne, Cologne, Germany;9Department of Otorhinolaryngology, Head and Neck Surgery, University of Giessen, Giessen, Germany;10Department of Oncology-Pathology, Karolinska University Hospital, Stockholm, Sweden;11Department of Clinical Science, Intervention and Technology, Department of Oto-Rhinolaryngology, Head and Neck Surgery, Karolinska University Hospital, Stockholm, Sweden;12Medical Unit Head and Neck, Lung and Skin Cancer, Karolinska University Hospital, Stockholm, Sweden;13Department of Surgical Sciences, Section of Otolaryngology and Head and Neck Surgery, Uppsala University, Uppsala, Sweden;14Department of Head and Neck Oncology, Gustave Roussy Cancer Campus, Villejuif, France;15Liverpool Head & Neck Centre, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, Liverpool, UK;16Precision Medicine Centre of Excellence, Patrick G Johnston Centre for Cancer Research, Queen’s University Belfast, Belfast, Northern Ireland, UK;17Regional Molecular Diagnostic Service, Belfast Health and Social Care Trust, Belfast, Northern Ireland, UK;18Department of Radiation Oncology/Otolaryngology—Head and Neck Surgery, Princess Margaret Cancer Centre, University of Toronto, Toronto, ON, Canada;19Institute of Head and Neck Studies and Education (InHANSE), Institute of Cancer and Genomics Sciences, University of Birmingham, Birmingham, UK;20Department of Otorhinolaryngology—Head and Neck Surgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland;21Department of Otorhinolaryngology, Head and Neck Surgery, Christian-Albrechts-University Kiel, Kiel, Germany;22Department of Otorhinolaryngology, Head and Neck Surgery, Christian-Albrechts-University Kiel, Kiel, Germany;23Cancer Epidemiology Research Programme, Catalan Institute of Oncology (ICO), Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L’Hospitalet de Llobregat, Barcelona, Spain
