The Role of Radiation Therapy

The primary treatment of melanoma is surgery. Radiation therapy is often recommended after surgery in primary melanomas that have features that indicate there is a high risk of the melanoma recurring near where it was excised.

Patients with the following characteristics are often treated with radiation to the skin after the primary melanoma has been excised:

1. melanoma where the pathology report indicates desmoplastic (scar-like) or neurotropic (in or near nerves) features
2. thick melanomas (> 4 mm deep), especially if ulcerated (raggedy surface) or associated with satellitosis (melanoma deposits separate from the primary area of melanoma
3. melanomas arising from the head and neck with certain high risk features, especially those involving the mucosa (lining the nose, mouth or throat).

Radiation therapy is also used in the setting of melanoma that has spread to regional lymph nodes. Surgery to remove lymph nodes usually provides excellent prevention of recurrence in the nodes, but certain features increase the risk of recurrence to as high as 30-50%, even after optimal surgery. In these cases, radiation therapy can reduce the risk of recurrence.

Patients with the following characteristics are often treated with radiation to the lymph node area after the lymph nodes have been removed:

1. extracapsular lymph node extension (extension of melanoma outside the lymph node)
2. Four or fewer involved lymph nodes
3. bulky lymphadenopathy (lymph nodes > 3 cm in size)
4. neck lymph node involvement
5. recurrent nodal disease (after prior treatment)
6. positive sentinel lymph node where a complete nodal removal of the area cannot be performed

Radiation therapy side effects depend on the location of treatment, but often include redness of the skin and mild fatigue. In an MD Anderson Cancer Center trial of 174 patients treated with postoperative radiation of skin melanomas of the head and neck metastatic to neck lymph nodes, acute tolerance of radiation was excellent and only 3 patients had significant late radiation complications. The rate of melanoma control at the site of radiation at 5 years was 88% whereas it would have been expected to be only 50% for patients who did not receive radiation. A recent update of this data, now with 267 patients, showed similar good results.