De-Escalated Adjuvant and Definitive Radiation Therapy Informed by DART 2.0 ctHPV-DNA

This study is testing whether radiation therapy doses can be safely reduced (de-escalated) for patients with oropharyngeal (throat) cancer, guided by a blood test called ctHPV-DNA that detects tiny fragments of HPV-associated cancer DNA in the bloodstream. The idea is that patients whose blood test turns negative quickly after treatment may need less radiation, reducing long-term side effects like dry mouth and swallowing difficulty. **You may be eligible if:** - You are 18 years or older - You have confirmed (or highly suspected) squamous cell carcinoma of the oropharynx (back of the throat, tonsils, base of tongue) - You are planned for surgery with curative intent, OR chemoradiation with cisplatin - No evidence of distant spread on imaging within the past 16 weeks - Your general health is good (ECOG score 0–1) **You may NOT be eligible if:** - Your cancer has spread to distant sites - You are ineligible for cisplatin-based chemotherapy - You are pregnant - You are unable to participate in all required follow-up visits Talk to your doctor to see if this trial is right for you.