Low‐dose total skin electron beam therapy in erythrodermic mycosis fungoides and Sézary syndrome: Results From the Prospective S‐MISR Study

Summary Background Erythrodermic mycosis fungoides (eMF) and Sézary syndrome (SS) often show delayed and non‐durable clinical responses to systemic therapies. Patients and Methods A total of 35 patients with eMF or SS were treated with total skin electron beam therapy (TSEBT). Response rates, patient‐reported outcomes, survival data, median time to next treatment (TTNT), and progression‐free survival (PFS) were evaluated. Results The analysis included 21 patients with SS and 14 with eMF. The median radiation dose was 12 Gy. At 3 months post‐TSEBT, the overall response rate was 89%. A total of 25 patients (71%) required subsequent systemic therapy. The median TTNT was 20 months, and the median PFS was 14 months. Patients reported marked reductions in pruritus, decreased skin disease burden, and improved health‐related quality of life scores. Notably, both TTNT and PFS were longer in patients who received subsequent therapy compared to those who did not. Grade ≥3 radiation‐related toxicity was observed in 6% of patients. In the translational arm of the study, several potential peripheral blood biomarkers were identified. Conclusions Low‐dose TSEBT is an effective treatment option for patients with eMF and SS, facilitating subsequent therapies and enabling long‐term disease control. The treatment is associated with significant quality‐of‐life improvements and low toxicity.