Radiotherapy is a localised treatment that uses high energy radiation to remove cancer cells. It does this by damaging the DNA of cells that are dividing. Radiotherapy may be used as an alternative to surgery in patients who are medically unfit for surgery or who can not have the melanoma removed surgically because it is too extensive or inaccessible. It is also used to relieve symptoms, with the purpose of making people feel more comfortable. For stage III melanoma, postoperative radiotherapy (external beam radiation) around the lymph area is sometimes considered for those who are considered as high risk for recurrence.
For those with brain metastases whole brain radiation or Stereotactic radiosurgery (SRS) may be used. SRS involves several powerful beams of radiation located at different angles around the head come together to focus precisely on the tumor. Gamma Knife is one of the most advanced forms of SRS.