Proton radiotherapy for malignant melanoma of the skin

Malignant melanoma, a tumor with reduced radiosensitivity, has been suggested to be overcome by a high-dose fractionation radiotherapy. The proton beam presents physical characteristics that enable such high-dose irradiation.

Our aim is to answer whether or not the proton beam can provide useful treatment for cutaneous melanoma.

Five primary melanomas (4 acral lentiginous and 1 superficial spreading type) and 3 metastatic lymph nodes of 3 different patients were irradiated using the proton beam with a total dose of around 100 Gy fractionated into single doses of approximately 10 Gy.

All the macular lesions and a tumor lesion of primary melanoma disappeared completely, and other tumor lesions regressed by 80-90%. The 3 metastatic lymph nodes also regressed by 50-90%. No severe radiation-related complication occurred.

Proton radiotherapy may prove to be a useful therapeutic modality for the management of cutaneous malignant melanoma.