Increased incidence of oropharyngeal cancer and p16 expression.

Conclusions: The incidence of oropharyngeal squamous cell cancer (OPSCC) in Finland has increased during the past decades. A similar change has been seen in the relative frequency of p16-positive head and neck squamous cell carcinoma (HNSCC). As p16 is a surrogate marker for human papilloma virus (HPV) infection, and as most p16-positive HNSCCs are OPSCC, HPV infection may have had a role in the observed increased incidence of OPSCC. Objectives: Numerous studies have shown that HPV is an independent risk factor for OPSCC. We aimed to use p16 as a surrogate marker of HPV infection to study its role as a possible risk factor in OPSCC. Furthermore, the change in the incidence of OPSCC in Finland was studied. Methods: HPV status was determined by p16 immunohistochemistry of 135 HNSCC tumour specimens retrieved from patients treated at the Helsinki University Central Hospital. Incidence data on OPSCC were obtained from the Finnish Cancer Registry. Results: The incidence of OPSCC in Finland increased from 0.66/100 000 person-years during 1989--1993 to 1.36 during 2004--2008. During the same period a significant increase in the relative frequency of p16 positive HNSCC tumours from 22% during 1990--1999 to 41% during 2000--2007 could be seen at our institution. In all, 85% of the p16-positive specimens were OPSCC. [ABSTRACT FROM AUTHOR]