Effect of postoperative radiotherapy in pT1pN1cM0 and pT2p/cN0cM0 oropharyngeal squamous cell carcinoma.

OBJECTIVES/HYPOTHESIS: Consulting of patients with oropharyngeal carcinoma, classified as pT1pN1cM0 and pT2p/cN0cM0, about postoperative radiotherapy is a precarious task as data are lacking. The aim of this study was to evaluate the effects of postoperative radiotherapy for patients with intermediate-stage oropharyngeal carcinoma. STUDY DESIGN: Multicentric retrospective study. METHODS: This analysis was conducted at seven Austrian institutions and included data of patients treated between 2000 and 2012. A total of 81 patients with oropharyngeal squamous cell carcinoma were included, of whom 33 patients received postoperative radiotherapy. p16 status determined by immunohistochemistry was available in 68 patients. RESULTS: Median follow-up was 47.9 months. Postoperative radiotherapy showed no benefits in regard to overall survival (P = .701). In contrast, disease-free survival was significantly shortened in all patients without postoperative radiotherapy (P = .001). When dividing the cohort in dependence of p16, p16-positive patients did not benefit from postoperative radiotherapy regarding overall and disease-free survival (P = .934 and P = .102), whereas p16-negative patients showed improved disease-free survival after postoperative radiotherapy (P = .007). Multivariate analysis showed that outcome of postoperative radiotherapy is dependent on p16 status. CONCLUSIONS: In terms of disease-free survival, patients with p16-negative tumors may benefit from postoperative radiotherapy, whereas survival of p16-positive patients is good regardless of additional treatment. LEVEL OF EVIDENCE: 4. Laryngoscope, 128:1075-1082, 2018.