Unlike traditional radiotherapy, which employs X-rays or gamma rays, proton beams exhibit a unique energy deposition pattern in matter. They deliver a lower dose as they enter the body and release most of their energy at a specific depth, known as the Bragg Peak. This Bragg Peak effect allows proton therapy to precisely concentrate a higher radiation dose on the tumor while minimizing damage to surrounding healthy tissues, achieving targeted "precision bombing" to cancer cell

In pursuit of proton therapy, Mr. C came to Guangzhou Concord Cancer Center . During examinations, abnormal thickening of his rectal wall was also discovered. Further colonoscopy and pathology results ultimately confirmed he had a second primary cancer: a rectosigmoid junction tumor.