46 NCCN Guidelines for Patients ® : Melanoma, 2018 4 Overview of melanoma treatments Radiation therapy Radiation therapy Radiation therapy uses a beam of high-energy rays to kill cancer cells. The rays damage a cell’s instructions for making and controlling cells. This either kills the cancer cells or stops new cancer cells from being made. For melanoma, radiation is often given using a machine outside the body. This method is called EBRT ( e xternal b eam r adiation t herapy). Radiation therapy is almost never used to treat the first (primary) melanoma tumor. Radiation therapy may help to prevent local recurrence after surgical removal of enlarged lymph nodes. But, this is less common with the advent of newer, more effective drugs for advanced melanoma. A more common use of radiation therapy for melanoma is as palliative treatment to relieve symptoms such as pain caused by the cancer, especially when it has spread to the bones. Palliative radiation therapy may also be used to treat the symptoms caused by metastatic melanoma. Palliative radiation therapy may also be used for lymph node, satellite, or in-transit metastases that can’t be treated with surgery. A wide range of radiation doses and schedules are effective. For melanoma, radiation therapy is most commonly used as palliative treatment or to treat brain metastases. Stereotactic radiosurgery or whole brain radiation therapy may be given for brain metastases. SRS ( s tereotactic r adio s urgery) is a type of external beam radiation therapy. SRS delivers a high dose of radiation to a very specific, small area of the body. Whole brain radiation therapy is EBRT aimed at treating the whole brain. Both types may be given as primary (first) treatment or adjuvant therapy for brain metastases. In selected patients with desmoplastic melanoma, adjuvant radiation therapy may be used to treat the tissue around the first (primary) melanoma tumor after wide excision based on certain factors. These factors include thicker desmoplastic melanoma removed with narrow surgical margins, local recurrence, or extensive neurotropism, also called perineural invasion. Neurotropism is when the melanoma cells surround and might invade nerves. Adjuvant radiation therapy may also sometimes be used for regional melanoma if it’s likely that the cancer will return in the area where nearby (regional) lymph nodes were removed. This area is called the nodal basin. Adjuvant radiation may be considered for selected patients after lymph node surgery based on certain features of the lymph node metastases. Side effects of radiation therapy Radiation therapy or any kind may have side effects. Side effects may occur during or after treatment (late side effects). It is important to talk with your doctor and fully understand the side effects when considering this treatment. Side effects of radiation therapy depend on the dose and the area being treated. Some of the physical side effects are temporary. For example, some skin changes may go away within 6 to 12 months after completing treatment. Some side effects of radiation therapy for melanoma are swelling, aches, heaviness in the treated area, sunburn-like skin changes, fatigue, and second cancer.