A Study of Radiation Therapy After Surgery in People With Oral Tongue Squamous Cell Carcinoma

Inclusion Criteria: * Age ≥ 18 * Surgical resection of all gross disease without evidence of residual loco-regional disease on simulation PET/CT. * pT1-2, or pT3 by DOI, pN0-2b Squamous Cell Carcinoma of the Oral Tongue confirmed on final surgical pathology. Patients must have: * at least two of the following pathologic risk features * LVI * DOI ≥ 4mm and ≤ 10mm OR * 1 or 2 pathologically positive nodes N1 to low volume N2b. OR DOI \>10 mm OR * \<=cT3N2b who undergo induction with near pCR (\<5% viable) or pCR at primary site * Primary specimen surgical margins ≥3 mm (if \<WPOI 5, margin can be \>= 2.2mm) * Signed informed consent form by the participant or their legally authorized representative (LAR) Exclusion Criteria: * N2c/N3 nodal disease * pT3 by size * \>2 pathologically positive nodes * Primary specimen surgical margin \< 3 mm (if \<WPOI 5, margin can be \>= 2.2mm) * Extensive Perineural Invasion (PNI); non-extensive PNI is permitted. * Extra-capsular extension in any pathologically positive lymph node * Prior or simultaneous invasive malignancy that, in the opinion of the PI, represents a competing risk of death equivalent to the patient's oral tongue squamous cell carcinoma. * Auto-immune conditions that would otherwise preclude radiation in the opinion of the PI (e.g. Scleroderma). * Lack of ability to understand and willingness to sign a written informed consent and complete questionnaires.