To evaluate prospectively the efficacy of a single fraction of high-dose radiotherapy in patients with Kaposi's sarcoma.

Between 1994 and 2004, 47 patients with Kaposi's sarcoma were treated at Hacettepe University, Department of Radiation Oncology. Thirteen (28%) patients received chemotherapy before radiotherapy and were referred due to recurrent or progressive disease or intolerance to chemotherapy. All lesions were treated locally with a 2-3-cm safety margin with 4-6-MeV electron beams. Radiotherapy consisted of a single fraction of 8 Gy in the first four years and 6 Gy thereafter.

The male:female ratio was 4:1. The median age was 61 years (range 18-87). Eight out of 47 patients (17%) had an underlying immunocompromised state, and one had a previous diagnosis of Hodgkin's disease. Of 203 fields treated, 51 and 152 fields were treated with 8 Gy and 6 Gy, respectively. Overall response rates (RR) at 12 months for 8- and 6 Gy were 93% and 86%, which were not statistically different. However, the difference between complete RRs at 12 months (93% and 60% for 8 Gy and 6 Gy respectively) was significant (p<0.0001). Progression-free survival and reirradiation rates were not significantly different. Side effects were tolerable in all but three patients with grade 2-3 fibrosis and edema.

Radiotherapy is an effective mode of treatment for Kaposi's sarcoma, and a single dose of 8 Gy is more effective in terms of complete RR compared to 6 Gy, though overall response and progression-free survival rates were similar.