HPV Status and second primary tumours in Oropharyngeal Squamous Cell Carcinoma

INTRODUCTIONS: The incidence of human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCCs) is rising in developed nations. Studies have shown that these virally mediated tumours are epidemiologically, clinically, and biologically different than other head and neck squamous cell carcinomas and traditional concepts of field cancerization may not apply to HPV-related oropharyngeal cancer. OBJECTIVE: The purpose of this study was to evaluate the rate of second primary tumors and the diagnostic yield of field cancerization work up in the upper aerodigestive tract in patients with HPV-related and HPV-unrelated oropharyngeal squamous cell carcinoma. DESIGN: Retrospective review. SETTING: Tertiary cancer care centers in Alberta. METHODS: Retrospective review of 406 patients diagnosed with OPSCC in Alberta between 2005 and 2009. HPV-status of tumours was determined by tissue microarray using immunohistochemistry staining for p16. MAIN OUTCOME MEASURES: Primary outcome: incidence of upper aerodigestive tract second primary tumours in p16-positive versus p16-negative OPSCC. Secondary outcomes: diagnostic yield of traditional field cancerization work-up in p16-positive versus negative patients. RESULTS: The overall rate of SPTs was 7.4% (30/406). The incidence rate of SPTs was significantly lower in p16-positive patients (0.7 per 100 patient-yrs vs. 8.5 in p16-negative, p < 0.0001). Field cancerization work-up for synchronous lesions in the upper aerodigestive tract, including panendoscopy and whole-body PET-CT, had decreased diagnostic yield in p16-positive patients (2.8% vs. 10.2% in HPV-negative patients, p=0.02). CONCLUSIONS: Patients with HPV-related OPSCC, who are non-smokers have decreased risk of developing second primary tumours in the upper aerodigestive tract and have low yield on field cancerization work-up. This study provides further evidence that virally mediated OPSCC are distinct and may benefit from alternate diagnostic pathways.