Objectives To determine the frequency by neck level of clinically known and occult lymph node metastasis in p16 positive oropharyngeal squamous cell carcinoma (p16+ve OPSCC). Design Retrospective study of 61 patients with p16+ve OPSCC whom had neck dissection and prior or simultaneous trans-oral surgery. Histopathology reports of neck dissection specimens were compared to preoperative clinical and radiological reports to determine the distribution of clinically known and occult nodal disease at each neck level and its concordance with preoperative findings. Positive and negative predictive values for pathological nodal disease (pN+ve or pN0) were assigned to clinically assessed node-positive (cN+ve) or node-negative (cN0) status at each neck level. Setting Single tertiary referral centre in the UK Participants 61 patients with p16+ve OPSCC with no prior head and neck cancer treatment. Main outcome measures Clinical, radiological, and pathological findings of nodal disease in the neck. Results Two-hundred individual neck level specimens were analysed. Seventy-seven levels were considered cN+ve, of which 83.1% (64/77) were also pN+ve. One hundred and twenty-three levels were considered cN0 of which 13% (16/123) were proven as pN+ve, demonstrating occult disease across various levels. This occult disease was identified in level II in 7 patients, level III in 6 patients and level IV in 3 patients, with no occult disease seen in cN0 level I or V. Conclusions These findings augment existing limited data on the distribution of occult nodes in OPSCC specific to p16+ve disease and reaffirm the rationale for dissecting at least levels II-IV in any cN0 neck.
