Lymphoscintigraphy Directed Elective Neck Radiation for p16+ Favorable Risk Oropharynx Cancer

Inclusion Criteria:

• Pathologically confirmed squamous cell carcinoma of the oropharynx

• Patients to be treated with bilateral neck radiation per current guidelines musthave either present (see below):

• Nodal status (based on staging manual, AJCC (American Joint Committee on Cancer) 8thed.): N0 (provided the tumor is within 1cm of midline) N1> 1 lymph nodes (on thesame side of the neck as the primary cancer) or cN3 (cranial nerve III) with nocontralateral neck adenopathy

• Tumor stage T1-2 that approaches within 1 cm but does not cross midline asappreciated radiographically and/or by the treating radiation oncologist or a headand neck surgeon

• CT with contrast and/or MRI with contrast performed within 56 days prior toregistration that does not demonstrate bilateral neck adenopathy. In the setting ofmedical contraindication to both CT and MRI contrast please contact the study PI

• PET/CT performed with 28 days prior to registration that does not demonstratebilateral neck adenopathy.

• Immunohistochemical staining for p16 that demonstrates moderate to severe stainingin at least 70% of cells.

• Patients must provide their smoking history prior to registration. Number ofpack-years = [Frequency of smoking (number of cigarettes per day) x duration ofcigarette smoking (years)]/20

• Patients must have clinically and/or radiographically evident disease that can beaccurately measured in accordance with RECIST criteria v. 1.1.

• Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0-1 within 56days prior to registration

• Age ≥ 18 years.

• Adequate hematologic function within 14 days prior to registration

• Adequate renal function within 14 days prior to registration

• Adequate hepatic function within 14 days prior to registration

Exclusion Criteria:

• Tumors that cross midline, regardless of T stage

• N2 adenopathy (bilateral neck adenopathy)

• Gross total excision of the primary site in a diagnostic procedure prior to eitherimaging and/or physical examination by registering physician.

• p16-negative squamous cell carcinoma

• Definitive clinical or radiologic evidence of metastatic disease or adenopathy belowthe clavicles

• Prior systemic therapy for the study cancer

• Prior head and neck cancer surgery that involved the neck (includes excisionalbiopsy)

• Prior radiation therapy to the head and neck that would result in overlap of treatedfields

• History of allergic reaction attributed to Technetium-99m-tilmanocept used inlymphoscintigraphy

• Uncontrolled intercurrent illness including, but not limited to, any othermalignancy, other ongoing or active infection, symptomatic congestive heart failure,unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/socialsituations that would limit compliance with study requirements.

• Pregnant or breast feeding