The prognostic utility of p16 overexpression and Human Papillomavirus DNA presence in base of tongue cancer patients: A retrospective cohort study in Region Örebro County.

Background: The overall good prognosis for Human Papillomavirus (HPV) driven base of the tongue cancer has prompted an increasing interest in whether this group could benefit from a less aggressive treatment regime. Different studies have drawn different conclusions as to which laboratory test should be used to identify these patients, using the surrogate marker p16, analyzing for HPV presence or both. Aim: The main purpose of this study was to investigate the presence of HPV-DNA and p16 in base of tongue cancer patients and their respective prognostic value, both used individually as well as combined. Material and methods: This was a retrospective cohort study consisting of 40 patients diagnosed with base of tongue cancer. The follow-up period was 5 years. Survival analysis was performed both depending on the combined results from the p16 immunohistochemistry analysis and the HPV DNA PCR, as well as separately. Results: Five-year survival rates were 73.9% for p16(+) and 17,6% for p16(-) subjects (p<0.001), 60.7% for HPV-DNA(+) and 25.0% for HPV-DNA(-) subjects (p=0.025). Five-year survival rates when combining p16 and HPV-DNA were 73.9% for p16(+)/HPV DNA(+), 25.0% for p16(-)/HPV DNA(-) and 0.0% for p16(-)/HPV DNA(+) (p<0.001). Conclusion: Our results add to previous research that p16 is a strong predictor of prognosis for base of tongue cancer patients, and could have the clinical implication of serving as a reliable tool for clinicians when determining prognosis and identifying patients who could benefit from treatment de-escalation in the future