EORTC cutaneous lymphoma RT recommendations
TL;DRReduced-dose RT recommended across indolent cutaneous lymphomas; local MF lesions 8-12 Gy in 2-3 fx, 1-yr local control ≥92%, no randomized evidence.
The de-escalation is not uniform: 4 Gy is endorsed for CD4+ small/medium T-cell LPD and many pcFCL/pcMZL, but gave inferior MF local control and worse outcomes in B-cell lesions >5 cm. The algorithm handles this with response-adapted escalation to cumulative 24 Gy rather than upfront conventional dosing.
The de-escalation is not uniform: 4 Gy is endorsed for CD4+ small/medium T-cell LPD and many pcFCL/pcMZL, but gave inferior MF local control and worse outcomes in B-cell lesions >5 cm. The algorithm handles this with response-adapted escalation to cumulative 24 Gy rather than upfront conventional dosing.
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Expert opinion from the EORTC cutaneous lymphoma tumour group, summarizing retrospective series and small prospective cohorts into a dose algorithm (Figs 2A/2B). No new patient data.
MF local lesions 8-12 Gy in 2-3 fx; low-dose TSEBT 8-12 Gy for palliation, up to 24 Gy before autologous SCT. CD4+ small/medium T-cell LPD 4 Gy in 2 fx; pcFCL/pcMZL start at 4 Gy with escalation to cumulative 24 Gy for residual disease or local failure.
Moves away from conventional 30-40 Gy, the standard until about 20 years ago, and builds on prior EORTC consensus treatment-selection recommendations. The 4 Gy question in cutaneous B-cell disease remains contested between small series and a long-f/u registry analysis.
Supporting series use varied endpoints (ORR, CR, local relapse, DOR, TTNT) and heterogeneous fractionation, so cross-series comparison is loose. QoL data after modern doses are sparse.
Low-dose local RT gives rapid symptom relief with low toxicity and few local relapses, but low-dose TSEBT relapses are common. Authors call for a prospective randomized dose trial with translational endpoints, and combined-modality work in advanced MF, SS and DLBCL leg type.
- Is 4 Gy with salvage escalation equivalent to upfront higher dose in pcFCL/pcMZL? n=52 · primary completion 2025-12 · 4 Gy/2 fx cohort, stage I-II indolent PCBCL
- Can systemic agents prolong remission after low-dose TSEBT? recruiting Anti-CCR4 Monoclonal Antibody (Mogamulizumab) and Total Skin Electron Beam Therapy (TSEB) in Patients With Stage IB-IIB Cutaneous T-Cell Lymphoma Phase 2n=43 · primary completion 2026-10 · mogamulizumab cycles continued post TSEB, MF IB-IIBrecruiting Mogamulizumab + Low-Dose Total Skin Electron Beam Tx in Mycosis Fungoides & Sézary Syndrome Phase 2n=30 · primary completion 2026-12 · phase 2 mogamulizumab + LD-TSEBT, MF/SS efficacyrecruiting Effectiveness of Concurrent Ultra-Low-Dose Total-Skin Electron Beam Therapy and Brentuximab Vedotin Given Quarterly Over 12 Months for Patients With Mycosis Fungoides Phase 2n=30 · primary completion 2027-01 · BV quarterly over 12 mo with ULD-TSEBT in MF
- Optimal consolidative RT dose in cutaneous DLBCL leg type
📚 Sources · 📄 1 paper
The longer read
The central argument of this document is that the historic dose ceiling for cutaneous lymphoma was set far above what these diseases need. For decades 30 to 40 Gy was treated as curative dosing, and the recommendation here is essentially to reserve that range for the minority of cases where lower doses demonstrably fail. The radiobiology section offers a mechanistic rationale, citing TREX1 upregulation above 12 to 18 Gy as a brake on RT-induced immune signalling, but that argument comes from preclinical and translational work and should not carry much weight in a dose decision on its own. The clinical case rests on retrospective response and local relapse data.
That evidence base is the main reason to hold the recommendations loosely rather than dismiss them. The series pooled in Tables 1 and 2 are small, mostly single-institution, and report different endpoints. Response rates near 100% in indolent histologies are expected almost regardless of dose, so ORR says little about the right dose. Local relapse and durability are the endpoints that could separate dose levels, and those need follow-up long enough to cover the late relapses typical of indolent B-cell disease. That is exactly where the data conflict: small series showed comparable in-field control between ultra-low and higher doses in pcFCL/pcMZL, while a larger registry analysis with longer follow-up found 4 Gy inferior. The authors do not settle the disagreement. They route around it with a response-adapted strategy, starting low and escalating to a cumulative 24 Gy for residual or recurrent disease. That is a reasonable pragmatic answer, but it assumes salvage after local failure is as effective as upfront higher dosing, and nothing in the source tests that.
The recommendations are most secure where the data are cleanest and stakes are lowest. CD4+ small/medium T-cell lymphoproliferative disorder at 4 Gy in two fractions, and MF plaques at 8 to 12 Gy, both have consistent local control, and the MF signal includes an explicit finding that 4 Gy underperforms, which gives a floor as well as a ceiling. The size caveat in B-cell disease (worse outcomes with 4 Gy for lesions over 5 cm) is the most practically useful selection detail in the paper, since it identifies a group where starting low may just add a treatment course.
For TSEBT the document is candid that low-dose regimens relapse often, and the case for lower doses is repeatability and toxicity rather than durability. Sézary syndrome and DLBCL leg type are framed as combined-modality problems, and the ongoing mogamulizumab and brentuximab trials with low-dose TSEBT are where that question will be answered. The call for a randomized dose trial is the right one; until it exists, these are well-reasoned defaults, not settled doses.