ESTRO 2025 - Abstract Book

S918

Clinical - Haematology

ESTRO 2025

Our meta-analysis demonstrated that radiotherapy resulted in superior PFS compared to no additional treatment to the bulky site in advanced HL (stages IIB-IV) after achieving complete remission to chemotherapy. Additional studies are needed to evaluate the impact of radiation dose on PFS and other survival parameters.

Keywords: Hodgkin lymphoma, Bulky disease, Meta analysis 4412

Digital Poster RADIATION THERAPY IN PRIMARY CUTANEOUS LYMPHOMAS PATIENTS: IMPACT OF “LOW” AND “HIGH” DOSES. Roberta MUNI 1 , Francesco R Filippone 1 , Angelo Di Naro 1 , Micaela Motta 1 , Fabio Piccoli 1 , Suela Vukcaj 1 , Michele Sala 2 , Maurizio G A Portaluri 1 1 Radiation Oncology, ASST PG23, Bergamo, Italy. 2 Radiology, ASST PG23, Bergamo, Italy

Purpose/Objective: Radiotherapy (RT) plays an important role in primary cutaneous lymphomas (PCL).

In the recent past 24-40 Gy in conventional fractions were recommended for solitary lesions or curative intent. Recommendations from the EORTC cutaneous lymphoma group, published in November 2024, suggest reduced dose of 8 Gy/2 fractions in aggressive subtypes as micosis fungoides (MF) and 4 Gy/2 fractions in less aggressive histologies with curative intent. We report our mono-institutional series of RT in curative and palliative setting focusing on radiation dose. Material/Methods: One hundred and forty lesions in 47 patients (pts) affected by PCL consecutively treated from 2009 to 2024, were included. Median follow-up was 66 months. More than half of the treated sites (55%) were represented by MF lesions (5 pts). Centrofollicular and marginal zone lymphoma were the most common subtypes (31 pts) corresponding to 34.2% of lesions. Electron RT was used in 92.1% of treatments with field size of 4 to 25 cm and energy of 4-16 MeV. Eleven lesions (7.8%) were treated with photon beams. A 5/10 mm bolus was used in 73.6% of treatments. Ninety/140 lesions (64.3%) received a total dose of 19.8-54 Gy (median 30 Gy) in 10-27 fractions. Low dose RT (4/8 Gy in 2 fractions) has been chosen in 5 MF patients with multiple disease relapse, partial overlaps with previous RT fields, old ages or other cancers, for a total of 50/140 lesions (35.7%), starting from 2021. Results: Overall 9 cutaneous recurrences were observed, in-field/marginal in 4 cases and out-field in 5 cases. Three pts were re-irradiated at the same site obtaining complete response (CR). In the “low dose MF” group 50% of the lesions had treated with a dose of 8 Gy/2 fractions, as ESTRO recommendations suggest, obtaining 100% CR. The remaining 50% received 4 Gy/2 fractions with a 96% CR. Nine pts were died at data time analyses, 2 for disease progression. With regard to toxicity, overall 2 pts who received 40 Gy on the scalp reported permanent alopecia. One patient treated on calf with 54 Gy had the most severe results with brown skin and muscle hypotrophy. Six pts had minor cosmetic effects. No toxicities were reported in pts treated with low doses. Conclusion: RT is an efficient and well tolerated treatment in PCL. In our series “very low dose” of 4 Gy/2 fractions, obtained high control rates also in aggressive subtypes as MF, allowing retreatment, low toxicities and limited access to hospital.

Keywords: Primary cutaneous lymphoma, RT doses

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