Background.Traditionally melanoma has been considered as a radioresistant tumor.However,recent observations regarding radiobiology and clinical response of melanoma have prompted physicians to re-evaluate the role of radiotherapy in the management of melanoma.Indeed,radiotherapy is frequently used in the treatment of metastatic melanoma but the role of this therapeutic approach in the primary tumor management is unclear.We report 4 cases of thick primary melanoma treated by interstitial brachytherapy.Case reports.Four patients(3 men,1 woman;age:73,74,79,84 years),three with lentigo maligna melanoma and one with nodular melanoma,were treated exclusively by interstitial brachytherapy.The thickness of the 4 tumors was more than 3 mm.This treatment was chosen either because of the impossibility of conservative surgery or because of a contraindication for general anesthesia.Median follow-up was 48 months [18 to 65 months] and we did not observe any local tumor relapse.The cosmetic and functional results of this therapy were excellent.Discussion.These four cases illustrate the possibility of obtaining good local control of thick primary melanoma by interstitial brachy therapy where surgery is impossible,although without challenging the standard surgical therapy for primary melanoma.Before our study,this treatment was used only in one study to treat melanoma patients.In this case however,interstitial brachy therapy was accompanied by surgery.Therefore,the findings reported here are the first to demonstrate the efficacy of this treatment when used as the sole treatment for primary melanoma.In conclusion,where surgery is difficult or impossible,interstitial brachytherapymay be used to treat primary melanoma with excellent local tumor control and a good cosmetic outcome. Background.Traditionally melanoma has been considered as a radioresistant tumor. Recently, regarding observations in radiobiology and clinical response of melanoma have prompted physicians to re-evaluate the role of radiotherapy in the management of melanoma.Indeed. Radiotherapy is frequently used in the treatment of metastatic melanoma but the role of this therapeutic approach in the primary tumor management is unclear. We report 4 cases of thick primary melanoma treated by interstitial brachytherapy. Case reports. Flow patients (3 men, 1 woman; age: 73,74,79, 84 years), three with lentigo maligna melanoma and one with nodular melanoma, were treated exclusively by interstitial brachytherapy. The thickness of the 4 tumors was more than 3 mm. This treatment was chosen either because because of impossibility of conservative surgery or because of a contraindication for general anesthesia. Median follow-up was 48 months [18 to 65 months] and we did not observe any local tumor relapse. cosmetic and funct ional results of this therapy were excellent. Discussion.These four cases illustrate the possibility of obtaining good local control of thick primary melanoma by interstitial brachy therapy where surgery is impossible, although without challenging the standard surgical therapy for primary melanoma. Before we study, this treatment was used only in one study to treat melanoma patients.In this case however, interstitial brachy therapy was accompanied by surgery. Beforefore the therapies, the findings reported here are the first to demonstrate the efficacy of this treatment when used as the sole treatment for primary melanoma In conclusion, where surgery is difficult or impossible, interstitial brachytherapymay be used to treat primary melanoma with excellent local tumor control and a good cosmetic outcome.