Validation of the TNM-8 AJCC Classification for HPV-Positive Oropharyngeal Cancers in Patients Undergoing Trans-Oral Robotic Surgery (TORS)

Abstract

High-risk human papillomaviruses (HPV) are associated with some oropharyngeal squamous cell carcinomas (OPSCC) and confer a significant prognostic factor. HPV-OPSCC have better survival outcomes compared to HPV negative tumours. The new TNM-8 AJCC staging (2018) is specific to HPV-associated OPSCC. In the re-classification study by the ‘International Collaboration on Oropharyngeal Cancer Network for Staging’, 98% of HPV-OPSCC patients were treated with primary chemo-radiation. The aim of our study was to validate the TNM-8 AJCC classification in HPV-OPSCC treated primarily with surgery (trans-oral robotic surgery or open). There were 102 patients with HPV-OPSCC treated between July 2009 and December 2014 at the Royal Adelaide Hospital. The median age was 57 years (range: 38-83) and mostly males (84.5%). 27.2% were active smokers and 50.5% reformed smokers. Early T stage cancer accounted for 72.8% (T1/2). Primary treatment was with surgery (TORS or open) and adjuvant therapy (70%) while primary chemo-radiation was the treatment for 30% of patients. Kaplan-Meier and Cox regression analyses were performed for both the 7th and 8th AJCC staging systems. The re-classification of this cohort to the AJCC 8th edition staging system resulted in a change of 54 patients from stage 4 to stages 1 and 2. This was mainly an effect of changes with N2a and N2b nodal disease being reclassified to N1 and demonstrates the prognostic effect of HPV in OPSCC. Survival outcomes were comparable with the ICON-S data. The new TNM-8 classification is therefore validated in a cohort treated, predominantly with primary surgery and adjuvant therapy. Funding Statement: None. Declaration of Interests: All authors declare no conflicts of interest. Ethics Approval Statement: Ethical approval was obtained from the CALHN REC, South Australia (Ref 13,407) to analyse clinical data on TORS.