Penn radiation oncologist Alexander Lin, MD, reviews the groundbreaking clinical study that established the equivalency of proton therapy to photon radiation (IMRT) as an adjunct for patients with HPV+ oropharyngeal cancer—finding in so doing that proton therapy can be used for deintensification of radiation treatment in this population. The study determined that proton therapy matched photon therapy in controlling cancer, and did so with fewer long-term side effects and better long-term outcomes, including survival.