Induction Chemotherapy Response-Guided Radiation for EBV-Associated Nasopharyngeal Carcinoma

Inclusion Criteria: * Participants must have histologically or cytologically confirmed (from primary lesion and/or lymph nodes) nasopharyngeal carcinoma. * Participants must have Epstein Barr virus (EBV)-associated nasopharyngeal carcinoma, defined as detectable (\> 0 copies/mL) circulating plasma EBV DNA on a qualitative or quantitative polymerase chain reaction (PCR)-based test. * Stage III-IVA disease (American Joint Committee on Cancer \[AJCC\], 8th edition \[ed.\]) with no evidence of distant metastasis at the time of diagnosis based upon all 3 of the following minimum diagnostic workup criteria: * History/physical examination by a medical oncologist or clinical oncologist or radiation oncologist or otolaryngology (ENT); * Evaluation of tumor extent with either one of the following: * MRI with contrast of the face, nasopharynx, and neck or CT with contrast of the face, nasopharynx and neck with ≤ 3 mm contiguous slices and bone windows to evaluate base of skull involvement; or * MRI of the nasopharynx and PET/CT (with contrast) of the neck * Imaging to rule out distant metastasis: * CT scan with contrast of the chest and abdomen (required) and the pelvis (optional) or a total body PET/CT scan (non-contrast PET/CT is acceptable); and * Only if clinically indicated: Bone scan only when there is suspicion of bone metastases (a PET/CT scan can substitute for the bone scan) * Started or planning to start platinum-based induction systemic therapy. * P…