In a randomized trial, researchers uncover evidence supporting a shorter treatment time for breast cancer patients. The study compared two separate dosing schedules of pencil-beam scanning proton therapy, the most advanced type of proton therapy known for its precision in targeting cancer cells while preserving healthy tissue to reduce the risk of side effects. Survival rates for breast cancer continue to improve due to advances, leading to increasing emphasis on reducing the long-term toxicity of cancer treatment, including radiotherapy. Prior to this study, all patients treated with proton postmastectomy radiotherapy (PMRT) had received a conventional 25- to 30-day course delivered...