P16 positivity and regression grade predict survival after neoadjuvant radiotherapy of OSCC.

Abstract

Survival after preoperative radiotherapy in locally advanced head and neck squamous cell cancer is associated with pathological response. The prognostic importance of p16 expression in these patients has not been established yet. Ninety-seven patients with oral squamous cell carcinoma, treated preoperatively with radiotherapy in combination with chemotherapy or cetuximab, were included in this retrospective analysis. Survival rates were estimated by the Kaplan-Meyer method. Pathological response was evaluated by histological analysis and p16 expression by immunohistochemistry. Overall survival after 2years was 66% for the entire group, 92% in the p16-positive and 62% in the p16-negative group, respectively. 12.4% of the tumours were p16-positive. P16 expression (HR 6.98, p=.05) and regression grade (HR 2.94, p=.001) had a statistically significant impact on prognosis. 83.3% of p16-expressing tumours were pathological responders. All p16-positive patients with pathological response were alive within the observation period. P16 expression is associated with prognosis in preoperatively irradiated OSCC patients. The association between p16 positivity, regression grade and improved survival provides a rationale for de-intensification strategies in patients with head and neck cancer who respond well to neoadjuvant therapy, a concept that is being tested in prospective clinical trials.