Prognostic Value of HPV Infection Assessed by p16 Immunohistochemistry and the Influence of Tobacco Usage in Oropharyngeal Cancers: Real World Scenario.

To find if an association could be established between Human Papilloma Virus (HPV) infection and oropharyngeal cancers (OPCs) in a group of patients known to be regular users of tobacco, and to determine the impact of HPV status on clinical outcomes.Case records of 212 patients with AJCC-7 (The American Joint Committee on Cancer 7th edition) stages II-IVB non metastatic squamous cell carcinoma of the oropharynx treated using radical radiotherapy with or without chemotherapy during the years 2015-2018 were retrieved. Formalin-fixed, paraffin-embedded blocks from oropharyngeal biopsies were available for 177 patients and were evaluated for p16 expression by immunohistochemical (IHC) staining. More than 50% nuclear staining with or without cytoplasmic staining was considered HPV+ . The association between tobacco use and HPV, as well as the influence of HPV status on survival outcomes were assessed. p16 expression was found to be positive in 23(13%) patients. Significant association was found between chewable tobacco usage and HPV positivity ( p  = 0.051). The median follow up was 20.5 months (range: 3-80). 5-year Overall Survival was 43.4% and 29.8% ( p  = 0.044) in HPV+ and HPV- patients, respectively. Local control was significantly better in HPV+ patients (38.6% vs. 25.3%, p  = 0.049). There was also a trend towards improved Disease-free Survival in HPV+ patients (31 months vs. 15 months, p  = 0.078). Though less in prevalence among the Indian population, improved outcomes in HPV+ OPC patients and widely available IHC HPV assays signifies the routine implementation of p16 testing in day-to-day clinical practice.