Is reduced-dose whole-brain radiotherapy also feasible in primary CNS lymphoma for curative or salvage purpose?

Purpose: Recently, reduced-dose whole-brain radiotherapy (WBRT) has been used to treat primary central nervous system lymphoma (PCNSL). However, whether reduced-dose WBRT is also an acceptable option for curative or salvage purposes has not yet been reported. We analyzed the clinical outcomes of patients with PCNSL who received radiotherapy for curative or salvage purposes and compared the clinical outcomes according to the WBRT dose. Methods: A total of 66 patients were divided into two groups: those treated with 30 Gy (2 Gy per fraction) or less WBRT (low-dose WBRT, n = 34) and those treated with more than 30 Gy WBRT (high-dose WBRT, n = 32). The median WBRT dose was 25.2 and 49.6 Gy in low-dose and high-dose WBRT groups, respectively. The median total radiotherapy dose, including the boost dose, was 50 Gy (range, 36.0-55.8 Gy). Results: The 3-year overall survival and progression-free survival were 77.8% and 29.8%, respectively. Intracranial relapse occurred in 31 patients (47.0%) at a median of 27 months after RT. Overall survival and progression-free survival did not differ between the two groups. The 3-year intracranial disease control rate did not differ between the two groups (35.2% vs. 41.6%, p = 0.300). Grade 3 or higher neurological toxicities were observed in six patients, of whom five were in the high-dose WBRT group. Conclusion: Reduced-dose WBRT in curative and salvage treatments for PCNSL had no significant negative effect on the intracranial disease control rate or survival. Therefore, without impaired efficacy, use of reduced-dose WBRT appears promising for reduction of neurotoxicity.