Today, most oropharyngeal squamous cell carcinoma (OSCC) is human papillomavirus (HPV) positive and HPV alone or in combination with p16 is reported to be a favorable prognostic factor for OSCC. Patients with tumors at other OSCC sites (OOSCC) are often included in the same treatment and study protocols as patients with tonsillar- and base of tongue SCC, even though the prevalence and clinical significance of HPV infection and the correlation to p16 in OOSCC still is unclear. Since tonsillar and base of tongue SSC cover roughly 90% of all OSCC, there is an obvious risk that there may be a misinterpretation of the results for OOSCC. We have in a previous minor study of 69 patients with OOSCC shown that only a minority (16%) to be HPV positive and 25% to be p16 positive. In addition, there was no complete correlation between HPV status and p16. Furthermore, no impact was seen on clinical outcome for the HPV-positive patients. We are therefore investigating the prevalence and correlation of HPV and p16 in OOSCC and their impact on survival a larger cohort from the Karolinska University Hospital, including patients from 2009-2014. This is of special interest since the International Union Against Cancer (UICC) in their eight edition changed the TNM-classification for p16-positive tumors for the whole OSCC-group.
All OSCC patients (C10.0–C10.9 and C50.1–C50.8) diagnosed between 2000 and 2014, in the County of Stockholm, Sweden, were included in the study. HPV-DNA was detected by PCR and p16 by immunohistochemistry. The study was conducted according to ethical permissions 2005/431-31/4 and 2005/1330-32 and 2009/1278-31/4 from the Ethical Committee at Karolinska Institutet, Stockholm, Sweden.
Preliminary results: 108 patients have been included so far (2000-2012) so far and of those 22 (20%) had HPV positive tumors. 68 tumors have been tested so far and 11 (16%) were p16 positive. Of the 22 HPVpositive tumours, 21 were also tested for p16 and only 8/21 (36%) were positive for both p16 and HPV.
Preliminary results show that the of HPV and/or p16 is much lower in OOSCC compared to earlier reports including all OSCC, or tonsillar and base of tongue cancer alone, the correlation between HPV-status and/or p16 in the tumors was not as strong as shown in previous studies including all OSCC or tonsillar SCC. We suggest that HPV/P16-positive OOSCC should not be treated in a similar way to HPV/p16 positive tonsillar and base of tongue cancer until larger studies have clarified the discordance between HPV and p16 overexpression and their clinical impact.