Lymphoma
2026-05-22
EORTC Cutaneous Lymphoma Tumour Group RT Recommendations
TL;DRExpert-opinion dose recommendations consolidating reduced-dose RT (4-12 Gy) across cutaneous lymphoma subtypes; no randomised trials underpin any of it.
The operative number for an RT reader is the dose floor, not the ceiling: 8-12 Gy in two or three fractions holds ≥92% 1-yr local control in MF, while 4 Gy underperforms there but suffices for CD4+ small/medium T-LPD (100% remission, no relapses). That split is the prescribing decision, and it argues against one ultra-low-dose default across subtypes.
In a patient with a symptomatic MF plaque or an indolent pcMZL/pcFCL lesion, this supports prescribing 8-12 Gy rather than a 30-40 Gy course; it does not extend to advanced MF, Sézary syndrome, or DLBCL leg type, where the authors concede combined-modality room for improvement.
The prescribing decision is where the floor sits by subtype: 8-12 Gy in two or three fractions holds ≥92% 1-yr local control in MF, while 4 Gy underperforms there yet suffices for CD4+ small/medium T-LPD. Pair a 4 Gy start in indolent B-cell disease with a four-month response assessment and escalation to 24 Gy.
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Expert opinion from the EORTC cutaneous lymphoma tumour group, tabulating published retrospective and small prospective series (Tables 1 and 2) into a dose algorithm (Figs 2A/2B). No pooled estimate, no protocol-registered synthesis.
Covers MF, Sézary syndrome, pcALCL, CD4+ small/medium T-LPD, pcMZL, pcFCL, and DLBCL leg type. Explicitly excludes the aggressive CTCL variants (subcutaneous panniculitis-like, gamma/delta, CD8+ epidermotropic, NK/T), where the authors say low-dose RT has a limited role.
MF plaques/tumours 8-12 Gy in two or three fractions; low-dose TSEBT 8-12 Gy for palliation and up to 24 Gy pre-autologous transplant; pcALCL few relapses at 20 Gy, palliative 2×4 Gy; CD4+ T-LPD 4 Gy in two fractions; DLBCL leg type consolidation reduced to 30 Gy, with 20 Gy reported post-systemic. Modalities named: electrons, photons, kilovoltage X-ray, brachytherapy.
The efficacy signal is uniformly high ORR across the tabulated series, but the discriminating result is dose-dependent local control: ≥92% 1-yr local control after low-dose MF RT versus an inferior rate at 4 Gy, and 28% vs 5% local relapse for 4 Gy vs 8-50 Gy in the ILROG registry series (p < 0.001).
Grade 3/4 toxicity is absent across most tabulated low-dose series. The one clear dose-toxicity signal in MF local RT is 27% grade 3/4 following 12 Gy versus 0% after 4-8 Gy; a prospective DLBCL leg-type cohort reported 14%.
The reference frame is the 30-40 Gy conventional standard that governed cutaneous lymphoma until roughly two decades ago. This document formalises the retreat from it, but does so on a base the authors concede is retrospective, so it codifies practice already in motion rather than establishing it.
The dose tables mix single-lesion and per-patient denominators and span decades of technique, so a 4 Gy series and a 40 Gy series are not comparing like populations. Several tabulated rows report dose comparisons as n.s. in cohorts far too small to exclude a real difference, which is not the same as equivalence.
The unresolved question is not whether reduced dose works but where its floor sits, and the answer looks subtype-specific rather than universal. The authors' own response-adapted proposal (escalate to a cumulative 24 Gy for residual disease or failure after 4 Gy) concedes that 4 Gy alone is a starting position, not a definitive prescription.
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