Jingyuan Chen

After a mastectomy, a woman often gets an implant, and then the chest is irradiated to kill any remaining cancer cells. Proton therapy is great because it hits the target precisely and spares the heart and lungs. But in some patients, a dense scar capsule forms around the implant: it squeezes the implant, making the breast hard and painful. This is called capsular contracture.

When a person receives radiation for a tumor in the head or neck, the rays pass through healthy tissue as well. Sometimes the jawbone starts to die afterward — a severe complication called osteoradionecrosis. The question isn't whether it happens, but how much the radiation dose itself increases the risk.