No benefit for regional control and survival by planned neck dissection in primary irradiated oropharyngeal cancer irrespective of p16 expression.

The aim of the study was to assess regional control and survival in primary irradiated oropharyngeal cancer patients with advanced neck disease (≥cN2a) receiving planned neck dissection (PND) irrespective of the nodal response compared to salvage neck dissection (SND) in case of regional persistence or reccurence in relation to tumoral p16 overexpression. 96 consecutive patients treated at the University Hospital of Zurich, Switzerland were included. Tissue microarray-based scoring of p16 expression was obtained. 5 years overall (OS) and disease-specific survival (DSS) in the PND and SND cohort were 70 vs. 57 % (p = 0.20) and 80 vs. 65 % (p = 0.14), respectively. Regional control in PND and SND achieved 95 vs. 87 % (p = 0.29), respectively. There was no statistically significant impact of neck treatment (PND vs. SND) on regional control or survival among patients with p16-negative tumors (5 years OS 59 vs. 50 %, p = 0.66; 5 years DSS 59 vs. 57 %, p = 0.89) nor among patients with p16-positive tumors (5 years OS 84 vs. 67 %, p = 0.21; 5 years DSS 95 vs. 81 %, p = 0.24). The type of neck dissection after primary intensity-modulated radiotherapy (IMRT) had no impact on regional control and survival even in human papillomavirus (HPV)-associated disease. Therefore we are convinced that based on the accuracy of newer diagnostic modalities the surveillance of a radiologically negative neck after primary chemoradiation (CRT) is oncologically safe irrespective of p16 expression of the tumor.