Background
International Lymphoma Radiation Oncology Group (ILROG) consensus guidelines on the use of radiotherapy for follicular lymphoma (FL), published in Blood 2019. Synthesizes evidence from FoRT, multiple retrospective series, and expert consensus to define indications, dose, and field guidelines for RT in follicular lymphoma.
Interventions and follow up
Arm A: N/A (evidence-based consensus guideline)
Arm B: N/A
Primary endpoint: Evidence-based RT recommendatio
mFollow up: N/A
Arm B: N/A
Primary endpoint: Evidence-based RT recommendatio
mFollow up: N/A
Results
Key Recommendations: Curative-intent RT for stage I–II FL: 24 Gy ISRT (preferred); 30 Gy if residual disease after chemotherapy. 5-yr DFS ~50–70% with RT alone for limited-stage FL. Palliative RT: 4 Gy (2 × 2 Gy) for low-burden symptomatic disease. 24 Gy for sites requiring durable palliation. ISRT replaces IFRT for all indications.
Adverse events
Main adverse events: N/A (guideline). RT toxicity depends on field location — generally well-tolerated at 24 Gy with modern IMRT/ISRT techniques.
Conclusions
RT remains a standard curative option for stage I–II FL, with ~50% of patients achieving durable remission with RT alone. Two-fraction palliative RT (4 Gy) is an effective option for symptomatic advanced-stage disease. ISRT is preferred over larger historical fields to reduce toxicity.
Key Limitations
Key Limitations: Randomized trials comparing RT alone vs observation vs rituximab for limited-stage FL are limited. The optimal strategy (watchful waiting, rituximab, or RT) for limited-stage FL is debated. The 24 Gy curative dose is extrapolated from retrospective data and FoRT findings, not a dedicated phase III trial.
Clinical Context
These ILROG guidelines are incorporated into NCCN and ESMO FL guidelines. Stage I–II FL can be treated with RT alone (24 Gy ISRT) with curative intent or combined with rituximab-based chemotherapy. Watchful waiting is also a valid option given the indolent biology of FL.
References
References: Brady JL et al, Blood 2019 (ILROG FL Guidelines)