Patients receive fludeoxyglucose F 18 (FDG) IV over 90 seconds prior to the initial scan. Patients undergo whole-body computed tomography (CT) imaging with contrast followed by positron emission tomography (PET) imaging (approximately 1 hour after FDG injection) for initial staging and simulation for radiotherapy treatment planning. After PET-CT evaluation, patients with locoregional disease are recommended for standard-care chemoradiotherapy. Patients with evidence of M1 disease that is confirmed by CT/MRI and/or biopsy are treated at the discretion of the attending clinician. During chemoradiotherapy, patients undergo PET-CT imaging, as described above, at the beginning of week 2 and during week 4 for treatment monitoring and early detection of recurrent or residual disease. Follow-up PET-CT scans are performed, as described previously, at 6 weeks and then at 3 months after completion of chemoradiotherapy.