Radiotherapy for indolent primary cutaneous B-cell lymphoma: an international multicenter ILROG analysis

Radiotherapy is an established treatment for low-grade primary cutaneous B-cell lymphoma. Recommendations on its use differ internationally, which prompted our group to conduct the present analysis. Twenty-two institutions participated in this international study. Patient eligibility required a diagnosis of limited (T1/T2) primary cutaneous marginal zone or follicle center lymphoma treated with radiotherapy between 1995 and 2023. Data were collected retrospectively until February 2024 in the framework of the International Lymphoma Radiation Oncology Group. Overall, 535 patients were analyzed. Predominant locations were the head (40%) and trunk (36%). Radiotherapy had a median dose of 24 Gy in fractions of 2 Gy. Complete responses were seen in 91% at a median time of 3.6 months following radiotherapy. There was no statistically significant difference between treatments ≤4 Gy or >4 Gy for complete or overall response rates (p=0.077 and p=0.056). However, there was an inferior duration of local control with ≤4 Gy (5-year local control 73% ± 12% vs. 96% ± 2%; p<0.001). Radiation dose was the main prognostic factor in the univariate and multivariate Cox analysis; however, higher doses did not translate into an overall survival benefit. Toxicities rarely exceeded grade 2 but were more frequent in the >4 Gy group. Radiotherapy remains an effective treatment option for indolent skin lymphoma with low toxicities. High response rates are observed with low doses ≤4 Gy. In comparison to conventional doses, these treatments have a shorter duration of local control but a favorable toxicity profile.

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Journal
Blood
Published
2026-03-13
DOI
https://doi.org/10.1182/blood.2025032050
Primary Topic
Cutaneous lymphoproliferative disorders research
Type
article
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article

Radiotherapy for indolent primary cutaneous B-cell lymphoma: an international multicenter ILROG analysis

Van Sim, Chris R. Kelsey, Y. Kirova, P. Johnstone et al.
Blood
Cutaneous lymphoproliferative disorders research
article

Radiotherapy for indolent primary cutaneous B-cell lymphoma: an international multicenter ILROG analysis

Van Sim, Chris R. Kelsey, Y. Kirova, P. Johnstone, U. Ricardi, Christina J. Hague, Michael Oertel, Dennis Görlich, S. Morris, Yolanda D. Tseng, Belinda A. Campbell, Atif A Hashmi, Khaled Elsayad, Christopher R. Weil, Jan Caspar Peeken, Bjorn Thomas, Tim Illidge, A. Ng, Hong In Yoon, John P. Plastaras, Philipp Linde, Teresa Easwaran, Randa Tao, M. Levis, Penny Q. Fang, Jürgen Dunst, Hans Theodor Eich, Daniel Edward Roos, Richard T Hoppe, Michael S. Binkley, Andrea Wittig, Bradley Ackerson, Michael Storck, Stephanie A Terezakis, Bouthaina S Dabaja, Rainer Fietkau, Felix Bock
article en

Abstract

Radiotherapy is an established treatment for low-grade primary cutaneous B-cell lymphoma. Recommendations on its use differ internationally, which prompted our group to conduct the present analysis. Twenty-two institutions participated in this international study. Patient eligibility required a diagnosis of limited (T1/T2) primary cutaneous marginal zone or follicle center lymphoma treated with radiotherapy between 1995 and 2023. Data were collected retrospectively until February 2024 in the framework of the International Lymphoma Radiation Oncology Group. Overall, 535 patients were analyzed. Predominant locations were the head (40%) and trunk (36%). Radiotherapy had a median dose of 24 Gy in fractions of 2 Gy. Complete responses were seen in 91% at a median time of 3.6 months following radiotherapy. There was no statistically significant difference between treatments ≤4 Gy or >4 Gy for complete or overall response rates (p=0.077 and p=0.056). However, there was an inferior duration of local control with ≤4 Gy (5-year local control 73% ± 12% vs. 96% ± 2%; p<0.001). Radiation dose was the main prognostic factor in the univariate and multivariate Cox analysis; however, higher doses did not translate into an overall survival benefit. Toxicities rarely exceeded grade 2 but were more frequent in the >4 Gy group. Radiotherapy remains an effective treatment option for indolent skin lymphoma with low toxicities. High response rates are observed with low doses ≤4 Gy. In comparison to conventional doses, these treatments have a shorter duration of local control but a favorable toxicity profile.

Blood
Guy's Hospital (GB), Royal Adelaide Hospital (AU), The University of Texas MD Anderson Cancer Center (US), Philipps University of Marburg (DE), The University of Melbourne (AU), Yonsei University (KR), Guy's and St Thomas' NHS Foundation Trust (GB), University of Washington (US), University of Utah (US), University of Münster (DE), University of Minnesota System (US), Peter MacCallum Cancer Centre (AU), Huntsman Cancer Institute (US), Duke Regional Hospital (US), University of Manchester (GB), Augenstern (DE), University Hospital Münster (DE), University Hospital Schleswig-Holstein (DE), Helmholtz Institute Mainz (DE), University of Minnesota, Duluth (US), Duke Medical Center (US), Universitätsklinikum Würzburg (DE), Helmholtz-Institute Ulm (DE), Stanford Medicine (US), California Ear Institute (US), CRUK Lung Cancer Centre of Excellence (GB), Comprehensive Cancer Center Erlangen (DE), University Hospital Cologne (DE), Dana-Farber Brigham Cancer Center (US), Institute for Medical Informatics and Biostatistics (CH), University of Rostock (DE), University of Turin (IT), University of Pennsylvania (US), Institut Curie (FR), University of Lübeck (DE), Stanford University (US)
Partnerships for the goals
Openalex Percentile: Top 21%
Cutaneous lymphoproliferative disorders research
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