Radiotherapy for human T-cell leukemia virus type 1-associated adult T-cell leukemia/lymphoma.

Adult T-cell lymphoma/leukemia (ATL) is an aggressively malignant peripheral T-cell neoplasm. Only a few studies have reported the use of radiotherapy (RT) for ATL. Therefore, the aim of this study was to clarify the efficacy of RT for ATL. We retrospectively reviewed 90 courses of RT administered to 19 consecutive ATL patients between 2008 and 2023. The subtypes included lymphoma (n = 8), acute (n = 7), smoldering (n = 3) and unknown (n = 1). Ninety lesions (cutaneous = 72, extranodal = 10, nodal = 8) were treated at a mean dose of 39.1 Gy/3.2 Gy (range, 24-60 Gy). Administration of RT for ATL lesions resulted in a combined complete response and partial response rate of 92%. At a mean of 47.5 months of follow-up (range, 0-102 months), local recurrence was not observed in 98.9% of the courses. A treatment response in terms of clinical symptoms was observed in 92% of the courses. The median survival time was 918 days. No acute grade ≥3 toxicity or any late toxicity was noted. In conclusion, RT was confirmed to be effective and safe for the treatment of local ATL lesions.