TNM 8 staging system beyond p16: Double HPV/p16 status is superior to p16 alone in predicting outcome in oropharyngeal squamous cell carcinoma

Purpose: The assessment of p16INK4a (p16) in oropharyngeal squamous cell carcinoma (OPSCC) has been incorporated into tumor classification, as p16 has been shown to impact survival probability. However, a recent study demonstrated that human papillomavirus (HPV) status in addition to p16 may have a better discriminatory effect on survival probability. This study aims to determine the impact of combined evaluation of p16 and HPV on prognosis. Methods: This was a multicenter, multinational analysis including retrospective and prospective cohorts of patients treated for primary OPSCC with curative intent, based on the data of the HNCIG-EPIC study. The primary outcome was to determine how the combined assessment of HPV and p16 status predicts prognosis of patients with OPSCC compared to p16 assessment alone. We employed multivariable analyses models to compute hazard ratios regarding survival. Analyses were stratified by stage, smoking status, and sub-anatomical region. Results: The study included 7654 patients, with approximately half of the tumors being p16-negative (50.3 %, n = 3849). A total of 9.2 % of patients had discordant p16 and HPV status (n = 704). HPV status significantly impacted overall survival and disease-free survival regardless of p16 status and across both UICC 8th stage I-II and III-IVb cancers. p16-positive/HPV-positive OPSCC patients exhibited the best survival probability. Conclusion: The detection of HPV had a significant impact on survival probability for OPSCC patients with both p16-positive and p16-negative tumors. HPV testing should be integrated in cancer staging, especially in regions of low attributable fraction, alongside p16 evaluation to ensure a comprehensive assessment of prognosis.