Changes in total skin electron beam therapy modalities for mycosis fungoides: A single-centre study

Mycosis fungoides (MF) is a highly radiosensitive disease. Total skin electron beam therapy (TSEBT) is an effective option that may allow prolonged response for several months. Recently, a low-dose regimen (12 Gy) has been reported more frequently, with less complete response than for standard doses (36 Gy) but better safety. Our aim was to compare patients treated with 12-Gy and 36-40-Gy TSEBT regimens at our centre for efficacy and safety.

This retrospective, monocentric study in Bordeaux University Hospital included all MF patients treated with 12-Gy or 36-40-Gy TSEBT between 2011 and 2020.

Patients presented with MF at the following stages: 15 T2, including 9 folliculotropic MF; 2 T3, including 1 folliculotropic; 8 T4, including 2 Sézary syndromes. The mean follow-up time after TSEBT was 43.5 months [range: 2-128] for the 36-40-Gy group and 25.2 months [range: 4-45] for the 12-Gy group. The 3-month overall response rate (ORR) was similar for both groups (84.6% for 36-40 Gy and 91.7% for 12 Gy), but there was a tendency to more complete response in the 36-40-Gy group (30.8% vs 8.3%, P=0.35). Progression-free survival (PFS) tended to be better in the 36-40-Gy group than in the low-dose group (15.7 months vs 5.3 months; P=0.28). Patients treated with low-dose TSEBT had a lower incidence of radiation dermatitis (16.7% vs 38.4%, P=0.42).

We confirm that TSEBT is an effective option, including at lower doses. Differences between low- and standard-dose regimens were not significant in our series. Although a low-dose regimen seemed to result in lower complete response and long-term efficacy rates in comparison with a standard dose, treatment at lower doses presents the advantage of repeatability, with fewer and weaker side effects, in the event of disease recurrence. Second-line treatments were mostly skin-directed in this group.