This review is a call for mindfulness and precision when applying TNM 8 in oropharyngeal cancers. Implications, intentions, and weaknesses of TNM 8 are addressed in light of our own investigations and the published literature. In TNM 8, the impact of p16INK4A status on the staging of oropharyngeal SCC highlights i) that underlying evidence is scarce, ii) its stage grouping exclusively has prognostic intention, and iii) that a noncritical application of TNM 8 might negatively impact the patients' survival as the perception of TNM 8 as having therapeutic intention may lead to de-escalating treatment regimens in p16INK4A-positive cases, specifically when grouped into stage I despite the presence of neck metastasis. If other parameters from HPV positivity that also have a negative impact on the patient's survival, such as smoking or the presence of comorbidity, are neglected in therapy planning, survival outcomes might even become worse. Future studies applying TNM 8 and further investigating the value of p16INK4A as surrogate marker for active HPV infections will identify whether or not changes in TNM 8 should have therapeutic implications in HPV-associated, only p16INK4A-positive cases or whether this impact additionally holds true for nontonsillar cancers.

Human papillomaviruses (HPV) cause a subset of head and neck cancers (HNSCC). HPV16 predominantly signs responsible for approximately 10% of all HNSCC and over 50% of tonsillar (T)SCCs. Prevalence rates depend on several factors, such as the geographical region where patients live, possibly due to different social and sexual habits. Smoking plays an important role, with non-smoking patients being mostly HPV-positive and smokers being mostly HPV-negative. This is of unparalleled clinical relevance, as the outcome of (non-smoking) HPV-positive patients is significantly better, albeit with standard and not with de-escalated therapies. The results of the first prospective de-escalation studies have dampened hopes that similar superior survival can be achieved with de-escalated therapy. In this context, it is important to note that the inclusion of p16^INK4A (a surrogate marker for HPV-positivity) in the 8th TMN-classification has only prognostic, not therapeutic, intent. To avoid misclassification, highest precision in determining HPV-status is of utmost importance. Whenever possible, PCR-based methods, still referred to as the "gold standard”, should be used. New diagnostic antibodies represent some hope, e.g., to detect primaries and recurrences early. Prophylactic HPV vaccination should lead to a decline in HPV-driven HNSCC as well. This review discusses the above aspects in detail.

The impact of smoking on survival in patients with squamous cell carcinoma of the head and neck is well established, despite some conflicting data in the literature. However, data on alterations of smoking habit following cancer diagnosis is sparse. In the present study, the effect of reduction of smoking compared with cessation on the course of disease was studied. Data from 643 patients with HNSCC from the tumor documentation registry of the Department of Otorhinolaryngology, Head and Neck Surgery of the Christian‑Albrechts‑University Kiel were collected and statistically analyzed, looking at pre‑ and post‑treatment smoking habit and survival. Alteration of smoking at the first diagnosis of HNSCC led to a significantly beneficial effect on survival outcomes compared with continued smoking, without significant differences between reduction and cessation of smoking. Detailed analysis revealed that this effect was solely dependent on patients treated by surgery only. Lifelong non‑smokers exhibited a significant survival advantage compared with active and former smokers, with no difference in survival between these last two groups. The positive influence of altered smoking habit following first time diagnosis on disease‑specific survival paralleled the negative direct effect of active smoking on therapy, which is predominantly attributed to peritumoral tissue hypoxia leading to impaired efficacy of radiochemotherapy (RCT). In the present study cohort, the positive effect of smoking habit alterations were primarily observed in patients treated by surgery only instead of RCT, possibly due to fewer perioperative complications. These findings indicated that patients should be encouraged to at least minimize smoking following cancer diagnosis. Furthermore, for survival estimates and therapy planning, former smokers should be considered as active smokers.

HPV-infection in patients with HNSCC is reportedly correlated with sexual behavior, age, and tobacco/alcohol-consumption. HPV-infections of the oral cavity are regarded as sexually transmitted. Comparable data of patient populations outside the U.S. are sparse or missing.