Total skin radiation therapy with low-dose helical tomotherapy for a patient with mycosis fungoides.

Total body skin irradiation with electron beams has been used for patients with mycosis fungoides (MF). Recently, helical tomotherapy was considered available for total body irradiation, although severe myelosuppression was frequently observed as an adverse event. We report the first case of low-dose helical tomotherapy in a patient with MF. An 87-year-old Asian male with an 18-year medical history of MF was referred to our department due to a rapidly growing skin lesion during systemic therapy. He decided to undergo low-dose total skin radiotherapy with helical tomotherapy. The total skin was treated by dividing into three parts (trunk, head, and lower extremities). Each part was treated with helical radiotherapy consisting of 10 Gy in 5 fractions, with the administration of 5 fractions per week. Once the skin lesion clearly disappeared after total skin radiotherapy, recurrence was detected in the lower abdominal wall in the radiation-treated field. Insufficient doses of radiation therapy cause early relapse. There is still no optimized dose for total skin irradiation in helical tomotherapy. Further radiation therapy dose trials are required to optimize the treatment schedule.