p16 status and interval neck dissection findings after a 'clinically complete response' to chemoradiotherapy in oropharyngeal squamous cell carcinoma

Objectives: To evaluate the histopathological findings from post-treatment neck dissection of p16 positive and negative oropharyngeal carcinoma cases, after completion of chemoradiotherapy, and to question the role of neck dissection after a 'clinically complete response' to chemoradiotherapy. Methods: Data were collected retrospectively from a cohort of patients treated with curative intent using chemoradiotherapy and post-treatment neck dissection. Primary tumours underwent p16 immunohistochemistry. Neck dissection specimens were examined for viable cancer cells. Results: A total of 76 cases were assessed. Viable cancer cells were detected from neck dissection in 29 per cent of p16 negative cases. Locoregional recurrence occurred in 12.9 per cent of p16 negative cases. The association between p16 positivity in the primary tumour and histopathologically negative neck dissection was significant (p < 0.05). Conclusion: p16 status appeared to be an independent marker of disease control for the cohort in this study. The data raise questions about the role of post-treatment neck dissection in p16 positive cases with a 'clinically complete response' to chemoradiotherapy.