Modified Recommendations for the Radiation Dose in Patients with Mycosis Fungoides and Localized Lesional Disease Based on a Retrospective Analysis of Treatment Outcomes.

Purpose: Primary cutaneous T-cell lymphomas are a rare and heterogeneous group of non-Hodgkin lymphomas predominantly affecting the skin. Treatment strategies are guided by diagnosis and disease stages. In patients with classical mycosis fungoides (MF) or folliculotropic mycosis fungoides, low-dose multiple fraction radiation therapy (RT) is a common approach for localized lesions, but optimal dose regimens are still to be defined. This study aimed to compare the efficacy of single-fraction low-dose RT (1 × 6 Gy) vs the well-accepted 2-fraction regimen (2 × 4 Gy) in patients with localized MF.

Methods and materials: A cohort of 54 patients with confirmed diagnoses of classical MF or folliculotropic MF received low-dose RT with either 1 × 6 Gy or 2 × 4 Gy between January 2017 and December 2022. Outcomes assessed included complete response (CR) rates, freedom from treatment failure, and toxicity.

Results: The CR rate for 311 treated fields was 86%. There was no significant difference observed in complete response rate between the 88 fields treated with 1 × 6 Gy (88% CR) and the 223 fields treated with 2 × 4 Gy (86% CR) (P = .87). The freedom from treatment failure at 3 years furthermore showed similar outcomes for both regimens (71% for 2 × 4 Gy and 79% for 1 × 6 Gy; P = .18). There were no significant treatment-related toxicities reported.

Conclusions: In this study, a single-fraction low-dose RT regimen (1 × 6 Gy) was shown to be comparable to the two-fraction regimen (2 × 4 Gy) in achieving CR for localized disease in patients with MF, offering a more convenient and patient-friendly option without compromising efficacy or safety. These findings support the incorporation of 1 × 6 Gy into clinical guidelines for the palliative management of MF.