Incidence Trends in Head and Neck Squamous Cell Carcinoma in Slovenia, 1983-2009: Role of Human Papillomavirus Infection

An increase in the incidence of oropharyngeal squamous cell carcinoma (OPSCC) was observed in several population-based registries and has been attributed to human papillomavirus (HPV) infection. In the present study, we aimed to assess the contribution of HPV infection to the burden of mucosal head and neck squamous cell carcinoma (HNSCC) in Slovenia. For this purpose, data from the nationwide Cancer Registry of Slovenia for cases diagnosed between 1983 and 2009 were analyzed to determine time trends of age-adjusted incidence rates and survival in terms of annual percentage change (APC) for HNSCC in potentially HPV-related and HPV-unrelated sites. In addition, determination of p16 protein, HPV DNA and E6/E7 mRNA was performed in a cohort of OPSCC patients identified from the prospective database for the years 2007-2008. In total, 2,862 cases of HNSCC in potentially HPV-related sites and 7,006 cases in potentially HPV-unrelated sites were identified with decreased incidence observed over the time period in both groups (-0.58; 95 % CI -1.28 to -0.13 and -0.90; 95 % CI -1.23 to -0.57). Regardless of the group, incidence trends for both genders showed a significant decrease in men and increase in women. In a cohort of 99 OPSCC patients diagnosed between 2007 and 2008, 20 (20.2 %) patients had HPV positive tumors and exhibited a superior outcome compared to HPV-negative patients. In conclusion, results of the epidemiologic and histopathologic study confirmed that HPV infection had no major impact on the incidence trends in the Slovenian patients with HNSCC and, specifically, OPSCC during the studied period.