Ultrahypofractionated Low-Dose Total Skin Electron Beam in Advanced-Stage Mycosis Fungoides and Sézary Syndrome

Abstract

To assess the safety and efficacy of ultra-hypofractionated low-dose total skin electron beam therapy (TSEBT) regimen in patients with advanced mycosis fungoides (MF) or Sézary syndrome (SS). In this multicenter observational study from five German centers, 18 total patients with MF/SS underwent TSEBT with a total dose of 8 Gy in two fractions. The primary endpoint was the overall response rate (ORR). 15 of 18 patients with stage IIB-IV MF or SS were heavily pre-treated with a median of four prior systemic therapies. The ORR was 88.9% (95%-confidence interval (CI): 65.3-98.6), with three complete responses (17%). At a median follow-up period of thirteen months, the median time to next treatment (TTNT) was 12 months (95%-CI: 8.2-15.8), and the median progression-free survival was 8 months (95%-CI: 2-14). Asignificant reduction in the modified severity-weighted assessment tool (mSWAT), total Skindex-29 score (Bonferroni-corrected P-value < 0.005), and all subdomains (Bonferroni-corrected P-values < 0.05) was observed after TSEBT. Half of the irradiated patients (N=9) developed grade 2 acute and subacute toxicities. One patient had confirmed grade 3 acute toxicity. Chronic grade 1 toxicity has been observed in 33% of patients. Patients with erythroderma/SS or prior radiation therapy appear at higher risk of skin toxicities. TSEBT with 8 Gy in 2 fractions achieves good disease control and symptom palliation with acceptable toxicity, greater convenience, and fewer hospital visits.