Role of salvage radiotherapy in relapsed/ refractory DLBCL in the rituximab era: A meta-analysis
PO-0912
Abstract
Role of salvage radiotherapy in relapsed/ refractory DLBCL in the rituximab era: A meta-analysis
Authors: KAZMI|, Farasat(1)*[farasat.kazmi@oncology.ox.ac.uk];Vellayappan|, Balamurugan(2);Kheng Wei|, Yeoh(3);Sin Huili|, Iris(3);Fei Tan|, Boon(3);Poh Shuxian |, Sharon(3);
(1)Churchill Hospital, Oncology, Oxford, United Kingdom;(2)National University Hospital Singapore, Radiation Oncology, Singapore, Singapore;(3)National Cancer Centre Singapore, Radiation Oncology, Singapore, Singapore;
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Purpose or Objective
The role of salvage radiotherapy in patients with relapsed/ refractory (r/r) Diffuse Large B-Cell Lymphoma (DLBCL) is unclear in the rituximab era. We sought to determine the efficacy and toxicity of radiotherapy for this group of patients.
Material and Methods
We searched MEDLINE and various conference proceedings for eligible studies where patients were treated with salvage radiotherapy for r/r DLBCL, excluding patients that received consolidation radiotherapy as first line treatment. Outcomes of interest were 2 and 5-year overall survival (OS-2, OS-5), 2 and 5-year freedom from progression (FFP-2, FFP-5) and Grade 3 or 4 adverse events (AE). We used random effects model to pool outcomes across studies and compared pre-defined subgroups using interaction test.
Results
We found 13 eligible non-comparative studies with methodological limitations identified. The studies included 412 patients who received rituximab based chemotherapy as first-line treatment. Of these, 2 were of a prospective design, 3 studies used peri-stem cell transplant radiotherapy, and 3 involved radiotherapy to primary mediastinal lymphoma. We found that salvage radiotherapy was associated with a OS-2 rate of 94% (95% confidence interval (CI) 84 – 95%, I2 = 55%), OS-5 rate of 83% (95% CI 76 – 89%, I2 = 64%), FFP-2 rate of 81% (95% CI 72 - 90%, I2 =74%), FFP-5 rate of 74% (95% CI 65 -82%, I2 = 74%), and Grade 3 or 4 AE rate of 8% (95% CI 2 -14%, I2 = 0%). Sub-group analysis showed that studies with prospective design had higher rates of OS-2 and OS-5 compared with studies of retrospective design (OS-2: 97% versus (vs) 81%, interaction P (IP) = 0.009; OS-5: 95% vs 75%, IP = 0.003) and studies which employed peri-stem cell transplant RT had lower rates of OS-5 compared to studies without stem cell transplant (59% vs 73%, IP = 0.02).
Conclusion
The meta-analysis provides evidence to suggest that salvage radiotherapy results in encouraging disease control and survival rates. The level of evidence was low emphasizing the need for high quality randomized trials to establish the optimal management strategy for r/r DLBCL.