Tobacco exposure as a major modifier of oncologic outcomes in Human PapillomaVirus (HPV) associated oropharyngeal squamous cell carcinoma

Abstract Background: The incidence of oropharyngeal squamous cell carcinoma (OPSCC) in the US is rapidly increasing, driven largely by the epidemic of human papillomavirus (HPV)-mediated OPSCC. Although survival for patients with HPV mediated OPSCC (HPV+ OPSCC) is generally better than that of patients with non-viral HPV+ OPSCC, this effect is not uniform. We hypothesized that tobacco exposure remains a critical modifier of survival for HPV+ OPSCC patients.Methods: We conducted a retrospective analysis of 611 OPSCC patients with concordant p16 and HPV testing treated at a single institute (2002-2013). Survival analysis was performed using Kaplan-Meier analysis and Cox regression. Recursive partitioning analysis (RPA) was used to define tobacco exposure associated with survival (p<0.05). Results: Tobacco exposure impacted overall survival (OS) for HPV+ patients on univariate and multivariate analysis (p=0.002, p=0.003 respectively). RPA identified 30 pack-years (PY) as a threshold at which survival became significantly worse in HPV+ patients. OS and disease-free survival (DFS) for HPV+ >30 PY patients didn’t differ significantly from HPV- patients (p= 0.72, p= 0.27, respectively). HPV+ >30 PY patients had substantially lower 5-year OS when compared to their ≤30 PYs counterparts: 78.4% vs 91.6%; p= 0.03, 76% vs 88.3%; p= 0.07, and 52.3% vs 74%; p= 0.05, for stages I, II, and III (AJCC 8th Edition Manual), respectively.Conclusions: Tobacco exposure can eliminate the survival benefit associated with HPV+ status in OPSCC patients. Until this effect can be clearly quantified using prospective datasets, de-escalation of treatment for HPV+OPSCC smokers should be avoided.