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.

This phase II trial is designed to rationally de-escalate adjuvant (Intensity Modulated Radiotherapy (IMRT) in the post-transoral surgery (TOS) setting in a study population consisting of patients with resectable oropharynx carcinoma, p16+ as confirmed by immunohistochemistry IHC, with a performance status (PS) of 0-1. Patients will be classified into one of three category/treatment groups (low-, intermediate-, and high-risk) according to their highest pathologically risk feature. Radiation will be given via an IMRT technique. For the high-risk patient group, a reduced, but slightly accelerated radiotherapy (RT) fractionation regimen of 50 Gy (HCC 18-034) in conjunction with cisplatin will be used compared to the standard 66 Gy and cisplatin. Low risk patients will transition to observation, intermediate risk patients will receive 30 Gy in 15 fractions of IMRT, and high risk patients will receive 50 Gy in 25 fractions (one day a week will include two treatments) plus 40 mg/m2 Cisplatin for 5 weeks. Patients who are not able to tolerate cisplatin will receive carboplatin instead.

Eligibility Criteria:
Inclusion Criteria:

* ECOG performance status of 0 or 1 or Karnofsky score 80-100.
* Newly diagnosed, histologically or cytologically confirmed SCC or undifferentiated carcinoma of the oropharynx and resectable oropharyngeal disease.
* Patients must be deemed eligible for a TOS procedure with no evidence of distant metastasis as determined by imaging studies.
* Biopsy-proven p16+ oropharynx cancer; the histologic evidence of invasive squamous cell carcinoma may have been obtained from the primary tumor or metastatic lymph node.
* Carcinoma of the oropharynx associated with HPV as determined by p16 protein expression using immunohistochemistry (IHC) performed by a CLIA approved laboratory.
* No prior radiation above the clavicles.
* Patients with a history of a curatively treated malignancy must be disease-free for at least two years except for carcinoma in situ of cervix, melanoma in-situ (if fully resected), and/or non-melanomatous skin cancer.
* Patients with congestive heart failure \> NYHA Class II, CVA/TIA, unstable angina, or myocardial infarction within the last 6 months prior to registration must be evaluated by a cardiologist and/or neurologist.
* Acceptable renal and hepatic function within 4 weeks prior to registration as predefined.

Exclusion Criteria:

* No evidence of extensive or "matted/fixed" pathologic adenopathy on preoperative imaging.
* Women must not be pregnant or breast-feeding due to the teratogenicity of chemotherapy.
* No intercurrent illness likely to interfere with protocol therapy or prevent surgical resection.
* No uncontrolled diabetes, infection despite antibiotics, or hypertension within 30 days prior to registration.