First-Line Treatment and Outcome of Elderly Patients with Primary Central Nervous System Lymphoma (PCNSL) – A Systematic Review and Individual Patient Data Meta-Analysis

Primary central nervous system lymphoma (PCNSL) is an aggressive lymphoma with devastating prognosis. High-dose methotrexate (HD-MTX) in combination with HD-cytarabine builds the backbone of current treatments. Elderly patients constitute 45% of cases, exhibit poor outcome and frequent iatrogenic toxicity. However, research efforts to optimize therapy in this subgroup have been neglected. On this background, we conducted a systematic review (SR) and individual patient data meta-analysis (IPDMA) to provide comprehensive evidence-based management strategy for elderly patients with PCNSL.

SR: We searched MEDLINE and EMBASE without language restriction. Eligibility criteria were prospective/retrospective observational studies or randomized trials (RCT) (all N>=10) that exclusively focused on first-line therapy/outcomes in immunocompetent PCNSL patients ≥60 years. Eligible studies were evaluated for methodological quality and reporting of the following baseline characteristics: Age, performance status (PS), involvement of deep brain structures (IDB), serum LDH at baseline, cerebro-spinal fluid (CSF) protein concentration elevation, neurotoxicity (as reported), specific co-morbidity indices, and functional status. For the IPDMA, investigators of eligible studies were asked to provide individual patient data. Minimal eligibility criteria: Age at baseline, details about first-line therapy, and follow-up information. If no data were available, studies were included in the SR, but not in the IPDMA. To maximize statistical power and generalizability, published/unpublished data from other international collaborators were included. Impact of different first-line treatments on overall survival (OS) was investigated using time dependent mixed effects multivariable Cox regression models (age and PS as fixed effects, study/database as random effect).

SR: We identified 13 eligible studies including 583 patients in total, median age 68–76, published from 1996–2011. Design of studies: prospective (3 multicenter [1 RCT]; 2 single center), retrospective (4 multicenter and single-center, respectively). Accrual of the RCT was recently finished, but publication is pending. From published studies, information about age and therapy was given throughout, for clinical performance in 77%, for LDH and CSF protein in 15%, and IDB in 38%. Functional status was reported in only one study. From the identified 13 studies, 261 individual patient data were available for our IPDMA and pooled with 408 patients from other databases; altogether 669 patients diagnosed from 1977–2011. Preliminary results IPDMA: 50% were male, median age 68 (60–70 [N=431], 70–80 [N=211], >80 [N=22]); median KPS was 60% (10–100%). Therapy regimens widely varied. Overall response to first-line treatment was 65% (45% CR, 19% PR). After a median follow-up of 23 months (1–171), 44% were still alive, with a 3-year OS of 32% [95%CI, 29–37%]. Grouping by time of diagnosis revealed improvement for patients diagnosed after 1997 (N=462) (P<0.001). In multivariate analysis, MTX-based poly-chemotherapy (CT) (N=474) was associated with improved OS (Hazard ratio [HR] 0.69, 95% CI 0.52–0.91) compared to non-MTX regimens (N=195); this was consistent among patients who received consolidating WBRT (HR 0.33, 95% CI 0.01–0.66) and those who did not (HR 0.46, 95% CI 0.23–0.89). In patients who received any MTX-based poly-CT, addition of CHOP-like components (N=90) was not associated with improved OS (HR 0.98, 95% 0.65–1.48). Although any WBRT showed an overall trend for superior OS, it was associated with a 4-fold risk increase for neurotoxicity (Odds Ratio 4.21, 95% CI 2.23–8.21). Further results of treatment patterns and explorative comparisons will be presented at the meeting.

This international meta-analysis revealed widely varying treatment approaches and demonstrates that prognosis for elderly PCNSL patients is still poor. However, improvement over the last decades was observed. MTX-based poly-CT was associated with better outcome compared to non-MTX containing approaches. The addition of CHOP-like regimens to HD-MTX did not improve outcome. WBRT was associated with better outcome, but also clearly increased risk of neurotoxicity. Prospective trials designed ad hoc for elderly PCNSL patients are promptly needed.

No relevant conflicts of interest to declare.