Balancing relapses versus cognitive impairment in primary central nervous system lymphoma: a single-center experience.

OBJECTIVES: The outcomes of primary central nervous system lymphoma (PCNSL) are much improved with multi-modality regimens. Unfortunately, in limited-resource countries, chemo-radiotherapy is the only option of curative-intent treatment. This study aimed to evaluate the effects of low-dose whole brain radiotherapy (WBRT) as a consolidation on disease control and long-term neurocognitive functions.

METHODS: We conducted a retrospective single-center study enrolling PCNSL patients from 2011 to May 2016 to evaluate the real-life treatment outcome and neurotoxicity from treatment especially radiotherapy.

RESULTS: Thirty-seven newly diagnosed immunocompetent PCNSL patients were treated with a high-dose methotrexate-based regimen with or without WBRT. The median age was 56 (range 16-78) years old. After chemotherapy, the overall response and complete response (CR) rates were 59.5% and 43.2%, respectively. All 6 partial response (PR) patients and 6 of 16 CR patients underwent radiotherapy. In 22 patients who achieved CR, the progression-free survival (PFS) of patients without WBRT was significantly inferior to the WBRT group with the hazard ratio of 4.7 (95% confidence interval 1.14-19.82, p = 0.03). The 3-year PFS were 35% and 78.75%, respectively, but there was no difference in overall survival. The serial Montreal Cognitive Assessment evaluations (20-72 months post chemotherapy) of 10 long-term CR patients revealed one dementia among three patients without WBRT and five mild cognitive impairments in seven patients with WBRT. Except for the dementia case, all the other patients can perform daily activities without assistance.

CONCLUSION: The low-dose WBRT consolidation is associated with lower PCNSL relapses with only mild neurocognitive toxicity.