title: Human papillomavirus type 16 is episomal and a high viral load may be correlated to better prognosis in tonsillar cancer.
abstract: The aim of our study was to investigate the physical state and the viral load of HPV-16 in tonsillar cancer and to correlate these findings with clinical outcome. To distinguish between integrated and episomal forms of HPV, 22 fresh-frozen tonsillar cancer samples were analysed by a method based on restriction enzyme cleavage, ligation and PCR (rliPCR). HPV-16 was detected in 11/22 and HPV-33 in 1/22 of the cancers, hence 12/22 (55%) of the tumours were HPV positive. Only extrachromosomal forms of HPV-16 were observed. Full-length episomal HPV was detected exclusively in 7/11 of the cancers, whereas both full-length and deleted forms of episomal HPV-16 were found in parallel in 2 other tumours. In 1 tumour only a deleted episomal form of HPV-16 was present. In the remaining HPV-16 positive tumour both full-length episomal as well as an 11 kbp PCR product were detected and if the 11 kbp product contained integrated HPV, or was off-size linearised episomal could not be determined. In 2 cervical cancer controls, HPV-16 was integrated and could be chromosome located. HPV-16 was quantified by real-time PCR and most tonsillar cancers contained between 10 to a few hundred copies of HPV per beta-actin. The 6 patients with tumour sections with > or =190 HPV-16 copies/beta-actin remained tumour free (p = 0.026) and had a better survival rate (p = 0.039) when compared to the 5 patients with tumours sections with < or =60 HPV-16 copies/beta-actin. In conclusion, HPV-16 is mainly episomal in tonsillar cancer. The viral load showed a wide distribution and the clinical outcome in our study was better when the HPV load was higher.
authors.affiliation: Department of Oncology-Pathology, Cancer Centre Karolinska R8:01, Karolinska Institute, Karolinska Hospital, S-171 76 Stockholm, Sweden. Hanna.Mellin@cck.ki.se
authors.forename: Hanna
authors.initials: H
authors.lastname: Mellin
authors.forename: Liselotte
authors.initials: L
authors.lastname: Dahlgren
authors.forename: Eva
authors.initials: E
authors.lastname: Munck-Wikland
authors.forename: Johan
authors.initials: J
authors.lastname: Lindholm
authors.forename: Hodjattallah
authors.initials: H
authors.lastname: Rabbani
authors.forename: Mina
authors.initials: M
authors.lastname: Kalantari
authors.forename: Tina
authors.initials: T
authors.lastname: Dalianis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D027383:Papillomaviridae / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction; D011379:Prognosis; D014067:Tonsillar Neoplasms / Q000401:mortality / Q000821:virology*; D002583:Uterine Cervical Neoplasms / Q000821:virology; D019562:Viral Load