Inclusion Criteria:  18 years and older. Primary OPSCC. Index cancer treated with TORS without adjuvant therapy. Any post-operative TNM classification. TORS performed on or before 31st July 2019.  Exclusion Criteria:  TORS preformed for diagnostic or palliative intentions. Known distant metastasis at time of TORS. Nasopharyngeal and thyroid cancers. Patients undergoing neoadjuvant or adjuvant chemotherapy, biotherapy, immunotherapy or radiotherapy to either the neck or primary site.