Patterns of Outcome in Human Papilloma Virus Positive Oropharyngeal Squamous Cell Carcinoma Treated Primarily with Radical Radiotherapy

Introduction: The aims of this study were to determine patterns of outcome and prognostic factors in human papilloma virus positive oropharyngeal squamous cell carcinoma (OPSCC+) treated primarily with radical radiotherapy. Materials and methods: We identified 54 patients at a tertiary hospital in South Australia who received treatment with curative intent for OPSCC+ with radical radiotherapy ± chemotherapy or cetuximab from 1st January, 2010 to 31st  March, 2017. We explored the effect of patient, tumour and radiotherapy factors on treatment outcomes. The primary endpoint was overall survival and the secondary endpoint was disease-free survival. Results: The median age was 59, with most patients being male (82%). The majority had advanced disease (89% stage IV). The median follow-up was 22.5 months. The one-year and two-year overall survival and disease-free survival rates were 89% and 79% and 77% and 68% respectively. Active smoking during radiotherapy was associated with trends to shortened overall survival (p=0.084) and reduced time to recurrence (p˃0.1). However, there was no statistically significant relationship between any other patient, tumour or treatment factors and disease-free or overall survival. Discussion: Despite advanced stage at presentation, radiotherapy ± concurrent systemic therapy results in favorable outcomes for OPSCC+. Active smoking during radiotherapy may compromise overall survival. We strongly recommend smoking cessation prior to commencing radiotherapy for OPSCC+. In addition, we note that smokers involved in de-intensification trials may be at increased risk of poor outcomes.