Transoral Surgical Resection Followed by De-escalated Adjuvant IMRT in Resectable p16+ Locally Advanced Oropharynx Cancer

This is a trial studying patients with human papilloma virus (HPV) positive oropharyngeal cancer with tumors that can be removed via transoral surgery. Following surgery, patients will be classified as either low, intermediate, or high risk based on the characteristics of the tumors. Low risk patients (Arm S) will receive no further treatment after surgery. Intermediate risk patients (Arm RT) will be treated with Intensity Modulated Radiotherapy (IMRT) after surgery. High risk patients (Arm CRT) will receive a combination of IMRT and chemotherapy after surgery. Patients will be followed for up to five years after the completion of treatment.