Role of 23.4 Gy upfront whole-brain radiation therapy following high-dose methotrexate for primary central nervous system lymphoma: a comparative analysis of whole-brain radiation therapy versus no radiation therapy

The role of radiotherapy in newly diagnosed primary CNS lymphoma: A descriptive review and a pragmatic approach to clinical practice

Earlier, prior to the development of effective systemic therapy, monotherapy with whole-brain radiotherapy (WBRT) was widely used to treat primary central nervous system lymphoma (PCNSL). Recently, chemotherapy, especially with high dose methotrexate (HDMTX), has largely replaced WBRT as upfront treatment, and the most accepted standard of care is induction with a combination drug therapy followed by consolidation therapy with either autologous stem-cell transplantation (ASCT) or radiation. Whilst WBRT is an effective component of treatment, it is occasionally associated with risk of permanent, irreversible neurotoxicity when doses of more than 30 Gy are used. Hence, there has been a strong focus on the optimization of radiotherapy (RT) which includes dose reduction in the consolidation phase. In this comprehensive review, we have summarized the progress on clinical results and evidence considering the role and use of radiation including combined treatment modalities, low-dose radiotherapy, and neurotoxicity. Finally, we present a practical approach to low-dose WBRT and boosting higher doses to the gross tumor that can be integrated into clinical practice.

Central Nervous System Prophylaxis and Treatment in Acute Leukemias

OPINION STATEMENT

Improvements in systemic therapy in the treatment of acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) have improved patient outcomes and reduced the incidence of CNS relapse. However, management of patients with CNS disease remains challenging, and relapses in the CNS can be difficult to salvage. In addition to treatment with CNS-penetrant systemic therapy (high-dose methotrexate and cytarabine), intrathecal prophylaxis is indicated in all patients with ALL, however is not uniformly administered in patients with AML without high-risk features. There is a limited role for radiation treatment in CNS prophylaxis; however, radiation should be considered for consolidative treatment in patients with CNS disease, or as an option for palliation of symptoms. Re-examining the role of established treatment paradigms and investigating the role of radiation as bridging therapy in the era of cellular therapy, particularly in chemotherapy refractory patients, is warranted.

Selective salvage radiotherapy could provide favorable outcomes in patients with refractory or relapsed primary central nervous system lymphoma

INTRODUCTION

To date, there is no relevant data supporting the role of salvage radiotherapy (sRT) in patients with refractory or relapsed primary central nervous system lymphoma (PCNSL). Herein, we aimed to investigate the impact of sRT in patients with refractory or relapsed PCNSL following upfront HD-MTX.

METHODS

We retrospectively reviewed 89 patients who had refractory (n = 16) or recurrent disease after an initial favorable response (n = 73); among them, 41 were treated with sRT and 48 were treated without sRT (nRT). Event-free survival (rEFS) and overall survival (rOS) after first recurrence were considered from the date of recurrence to date of each event.

RESULTS

Overall, the first failure was diagnosed at a median of 11.0 months [interquartile range (IQR), 5.6-26.4] after first treatment. More than half of the patients had recurrent disease involving initial tumor bed (n = 47), deep structure (n = 67), and multiple lesions (n = 58). Among 19 patients who were initially treated with 23.4 Gy of whole brain RT, 10 patients received sRT as a re-irradiation; other 31 patients in sRT group were RT naïve patients. There was no significant difference in tumor characteristics between sRT and nRT group. Overall and complete response after salvage treatment were 80% and 48%, respectively; sRT provided higher overall response rate than nRT (93% vs. 69%, p = 0.011). With a median follow-up of 14.3 months (IQR, 7.9-31.4), 2-year rEFS and rOS rates were 27% and 57%, respectively. There were no differences in rEFS and rOS according to sRT (sRT vs. nRT, 26% vs. 28%, p = 0.730; 63% vs. 50%, p = 0.690). Poor performance, recurrence interval < 8 months, and unfavorable response following salvage treatment were associated with inferior rEFS and rOS. Additionally, sRT and stem cell transplantation improved response rate independently after multivariate analysis for complete/partial response.

CONCLUSIONS

We found favorable response rate and comparable survival outcomes following sRT compared with non-local treatments for patients with refractory/relapsed PCNSL. Further studies of patient selection could stratify patients who can benefit from sRT.