Phase II Randomized-registry Embedded Study of Lymphoscintigraphy for Oropharyngeal Neoplasms to Enable Risk-adapted Nodal Guidance for Robotic Surgery and/or Radiotherapy (LONE-RANGR2)

Inclusion Criteria: * Newly diagnosed histopathologically-proven p16+ and/or HPV+ HNSCC of the base of tongue or faucial tonsil * cT1-2N0-1 per AJCC 8th edition staging. * Tumor does not cross midline, and must be \>1cm from midline * For tonsil tumors, the primary may extend onto the palate or into the BOT but still be \>1cm from midline * No evidence of contralateral neck disease on contrast MRI, CT Head/Neck, PET/CT, or lymphoscintigraphy nor retropharyngeal lymphadenopathy. * Able to undergo lymphoscintigraphy procedure * No contraindications for SLNM, adjuvant chemotherapy, RT nor adjuvant/definitive radiotherapy. * ECOG 0-1 * Age \>18 years * Ability to understand and the willingness to sign a written informed consent document. Exclusion Criteria * Previous HN Cancer except small skin cancers. * Any retropharyngeal lymphadenopathy on either MRI, CT, or PET/CT * Contralateral neck nodal disease radiographically detected per routine diagnostic imaging or SPECT-CT. * Distant metastatic spread at the time of inclusion * Chemotherapy or surgery (for the present tumor), prior to inclusion. * Previous radiation treatment in the head and neck region, for any reason, except for cutaneous lesions that would not lead to overlap with definitive bilateral neck irradiation * Recurrent or second primary tumor in the head and neck region * Non-tongue base or non-faucial tonsil primaries * Prior history of regionally advanced or distant spread cancers * Pregnancy or no active contrac…