Latest Guidelines for Radiotherapy in Lymphoma
Modern radiotherapy for lymphoma has evolved to use significantly reduced volumes (involved-site radiotherapy, ISRT) and lower doses (20-30 Gy) compared to historical approaches, with treatment tailored to lymphoma subtype and stage. 1, 2
Key Principles of Modern Radiotherapy
Volume Reduction: Involved-Site Radiotherapy (ISRT)
The International Lymphoma Radiation Oncology Group (ILROG) established ISRT as the standard approach, replacing extended-field and traditional involved-field techniques. 1, 2
ISRT defines the clinical target volume (CTV) based on PET-defined pre-chemotherapy sites of involvement with a 1.5 cm cranio-caudal expansion along lymphatic pathways, constrained by anatomical boundaries (bone, muscle, air cavities). 3
Planning should utilize contrast-enhanced 3mm contiguous CT scans with three-dimensional definition of volumes using GTV (gross tumor volume), CTV (clinical target volume), and PTV (planning target volume) conventions. 3
For optimal imaging scenarios, involved-node radiotherapy (INRT) can be used, which is even more conformal than ISRT. 1
Dose Reduction Guidelines
For Hodgkin lymphoma in combined modality therapy: 30 Gy is the standard dose, with 20 Gy potentially sufficient for early-stage low-risk disease. 3, 1
For aggressive non-Hodgkin lymphoma: 30 Gy maximum is recommended. 3
For indolent lymphomas: 24 Gy is recommended, with some evidence supporting even lower doses. 3, 2
Hodgkin Lymphoma-Specific Guidelines
Early-Stage Favorable Disease (Stage I-II without risk factors)
Standard treatment: 2 cycles of ABVD followed by 20-30 Gy involved-field radiotherapy. 4, 5
The lower dose of 20 Gy may be sufficient in this setting when combined with chemotherapy. 3
Early-Stage Unfavorable Disease (Stage I-II with risk factors)
Standard treatment: 4 cycles of ABVD followed by 30 Gy IF-RT. 6, 4
For patients under 60 years eligible for intensive treatment: 2 cycles BEACOPPescalated + 2 cycles ABVD + 30 Gy IF-RT provides superior freedom from treatment failure. 6
Advanced-Stage Disease (Stage III-IV)
Radiotherapy is limited to residual masses >1.5 cm after chemotherapy completion. 6
Dose: 30 Gy to residual disease sites. 6
Radiotherapy may be omitted in patients with residual lymphoma but negative FDG-PET after chemotherapy completion. 6
PET-guided treatment adaptation using Deauville criteria is increasingly used to determine need for consolidative radiotherapy. 4, 5
Non-Hodgkin Lymphoma-Specific Guidelines
Diffuse Large B-Cell Lymphoma (DLBCL)
For limited stage (I-II) disease: Combined modality therapy with chemotherapy followed by consolidative radiotherapy is standard. 6
Dose: 30 Gy for aggressive NHL. 3
Follicular Lymphoma and Indolent Lymphomas
For localized disease (stage I or non-bulky stage II): Radiotherapy alone at 24 Gy is potentially curative. 7, 2
Radiotherapy is particularly valuable in older patients where chemotherapy tolerance may be limited. 7
For marginal zone lymphoma (MZL): 24-30 Gy locoregional radiotherapy is first-line for localized disease. 8
Mantle Cell Lymphoma
For limited non-bulky stage I-II: Involved-field radiotherapy (30-36 Gy) may achieve long-term remissions, though data are limited. 6
For stage I-II with large tumor burden: Systemic therapy as for advanced stages, with radiation consolidation considered based on tumor location. 6
Primary Cutaneous Lymphomas
For localized cutaneous B-cell lymphoma: Radiotherapy is the primary treatment modality. 6
For primary cutaneous CD30+ anaplastic large cell lymphoma: Radiotherapy alone for localized disease. 6
For other cutaneous T-cell lymphomas: Radiotherapy for localized disease, with total skin electron beam (TSEB) for extensive skin involvement. 6
Technical Considerations
Modern Planning Techniques
Intensity-modulated radiotherapy (IMRT), breath-hold techniques, image-guided radiotherapy (IGRT), and 4D imaging should be implemented when they significantly decrease normal tissue damage risk. 1, 2
These advanced techniques enable very significant reductions in radiation doses to normal organs without compromising lymphoma coverage. 9
Critical Pitfalls to Avoid
Do not use extended-field or traditional involved-field techniques based on nodal stations—these are obsolete. 1, 2
Do not use doses higher than 30 Gy for Hodgkin lymphoma or aggressive NHL in combined modality settings—this increases late effects without improving disease control. 3, 1
Do not omit PET/CT imaging when available—it is essential for defining treatment volumes and assessing response. 4, 3
Avoid replacing radiotherapy with additional chemotherapy in localized disease, as this may lead to suboptimal outcomes and increased toxicity. 7
Quality of Life and Late Effects Considerations
The dramatic reduction in treatment volumes and doses has substantially decreased risks of long-term adverse effects compared to historical approaches. 9, 1
Cardiotoxicity and pulmonary toxicity remain concerns requiring pre-treatment evaluation and long-term surveillance. 5
Fertility preservation counseling should be offered to young patients prior to treatment initiation. 4, 5
The risk of secondary malignancies with modern limited-field, low-dose radiotherapy is significantly lower than with historical extended-field approaches. 9, 7