 5. Definitive Patients: Histology confirmed unknown primary T0N1-2bM0 or oropharynx Stage I, II, III, IV TX, T1-T2, favorable T3 exophytic N0-N2b, M0, small volume primary and nodal, not requiring chemotherapy during RT i.e., induction chemo is acceptable as well as concurrent biological therapy e.g., Cetuximab, squamous cell carcinoma AJCC Staging of HNSCC. Lymph nodes bilaterally of the neck are at risk for metastatic disease and require irradiation per clinical judgment. 