Transoral Surgery Followed By Low-Dose or Standard-Dose Radiation Therapy With or Without Chemotherapy in Treating Patients With HPV Positive Stage III-IVA Oropharyngeal Cancer

PRIMARY OBJECTIVES: I. Accrual, risk distribution, and surgical quality will be used to determine the feasibility of a prospective multi-institutional study of transoral surgery for HPV positive (+) oropharynx cancer followed by risk-adjusted adjuvant therapy. II. To assess the oncologic efficacy following transoral resection and adjuvant therapy in patients determined to be at "intermediate risk" after surgical excision, the 2-year progression free survival (PFS) rate will be examined. SECONDARY OBJECTIVES: I. To estimate the patient distribution with various histologic risk features. II. To assess and compare early and late toxicities associated with transoral surgery (TOS) and the different doses of adjuvant postoperative radiotherapy (PORT). III. To evaluate swallowing function before and after TOS and risk-adjusted adjuvant therapy. IV. To evaluate quality of life (QOL), swallowing perception and performance, voice outcomes, and head and neck symptoms. TERTIARY OBJECTIVES: I. To correlate tumor TP53 mutation and other associated mutation profile with pathologic findings, with PFS and other outcome parameters in patients with resectable HPV-associated oropharyngeal squamous cell carcinoma (OPSCC) after the above treatments. II. To evaluate radiation resistance markers, including excision repair cross complementing 1 (ERCC1) single nucleotide polymorphism and protein expression, and correlate them with treatment efficacy. III. To investigate the usefulness of biomarkers in predicting progression-free survival and biomarkers, including tumor ERCC1, epidermal growth factor receptor (EGFR), plasma cytokine/chemokines, cellular immunity to HPV, and oral HPV deoxyribonucleic acid (DNA). OUTLINE: All patients undergo transoral surgery (TOS) in Step 1. ARM S: Patients undergo transoral resection of the oropharyngeal tumor. Then patients are classified by risk status (low risk, intermediate risk, or high risk) in Step 2 and assigned to the appropriate treatment group. Patients classified as intermediate risk are randomized to arms B or C. ARM A (low risk; observation): Patients receive observation. ARM B (intermediate risk): Patients undergo low-dose (50Gy) intensity modulated radiation therapy (IMRT) once daily (QD) over 25 fractions. ARM C (intermediate risk): Patients undergo standard-dose (60Gy) IMRT QD over 30 fractions. ARM D (high risk): Patients receive IMRT at 66 Gy QD for 33 fractions. Patients also receive cisplatin intravenously (IV) over 60 minutes on days 1, 8, 15, 22, 29, 36, and 43 during radiation therapy. After completion of study treatment, patients are followed up every 3 months for 2 years and then every 6 months for 3 year.