They can be treated again at the same site if a relapse occurs. Almost all cancers require watching out for a return of the cancer. Monitoring may last for 2 to 10 years, depending on the type of cancer. Side effects occur because any living tissue is sensitive to radiation. They result when normal cells that are damaged by radiation aimed at cancer cells.
Side effects can be acute, mild, and temporary, or they can be more serious and permanent.
Normal cells that are rapidly growing or regenerating are more prone to side effects. Examples are bone marrow, intestines, hair follicles, the lenses of the eyes, kidneys, liver, and lungs. The brain, heart, cartilage, and bone are less sensitive. Some side effects are acute, but go away on their own. These include hair loss, skin burn, nausea, fatigue, mouth sores, diarrhea, and drops in blood cell counts.