title: Incidence of tonsillar cancer in northern Sweden: Impact of human papilloma virus.
abstract: The incidence rate of tonsillar cancer is increasing worldwide. The current study identifies a parallel increase in the incidence of tonsillar cancer, human papilloma virus (HPV) and p16 expression among a population from northern Sweden, a sparsely populated area, confirming the strong association between p16 and HPV infection in tonsillar tissue. Data from the Swedish Cancer Registry was assessed to identify cases of tonsillar cancer in the northern territorial area of Sweden. HPV DNA was extracted from paraffin embedded diagnostic biopsies and detected by polymerase chain reaction using general primers Gp5+/6+ and CpI/IIG. Expression of p16 was identified by immunochemistry. Patients were grouped into urban or rural residence categories. A total of 214 cases were identified, comprising 155 (72.4%) men and 59 (27.6%) women, and 65 of these patients, who presented between 2000 and 2012, were analyzed. The overall median age for the analyzed patients was 58 years; 48 (74%) were males (median age, 57.5 years) and 17 (26%) were females (median age, 65 years). Of the 65 specimens, 59 (91%) were positive for HPV, and 62 (95%) expressed p16. The incidence of tonsillar cancer in the cohort demonstrated a 2-fold increase between 1990 and 2013; specifically, a 2.7-fold increase was observed in men whilst the female group exhibited only a small increase. These findings demonstrate a strong association between p16 expression and HPV infection in tonsillar malignancies. The incidence of HPV-positive tonsillar cancer has increased in recent years, even in sparsely populated regions, as demonstrated in northern Sweden.
authors.affiliation: Department of Clinical Sciences, Division of Otorhinolaryngology, Umeå University, S-901 85 Umeå, Sweden.
authors.forename: Christos
authors.initials: C
authors.lastname: Loizou
authors.affiliation: Department of Clinical Sciences, Division of Otorhinolaryngology, Umeå University, S-901 85 Umeå, Sweden; Department of Surgical Sciences, Division of Otorhinolaryngology, Uppsala University, S-751 85 Uppsala, Sweden.
authors.forename: Göran
authors.initials: G
authors.lastname: Laurell
authors.affiliation: Department of Radiation Sciences, Division of Oncology, Umeå University, S-901 85 Umeå, Sweden.
authors.forename: David
authors.initials: D
authors.lastname: Lindquist
authors.affiliation: Department of Radiation Sciences, Division of Oncology, Umeå University, S-901 85 Umeå, Sweden.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Öfverman
authors.affiliation: Department of Radiation Sciences, Division of Oncology, Umeå University, S-901 85 Umeå, Sweden.
authors.forename: Kristina
authors.initials: K
authors.lastname: Stefansson
authors.affiliation: Department of Medical Biosciences, Division of Pathology, Umeå University, S-901 85 Umeå, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Nylander
authors.affiliation: Department of Clinical Sciences, Division of Otorhinolaryngology, Umeå University, S-901 85 Umeå, Sweden.
authors.forename: Katarina
authors.initials: K
authors.lastname: Olofsson
keywords: head and neck cancer; human papilloma virus; immunohistochemistry; incidence; p16; tonsillar cancer