Evaluation of progression-free survival as a surrogate end point in primary CNS lymphoma: a systematic review and meta-analysis

Purpose: To evaluate progression-free survival (PFS) as early surrogate endpoints for overall survival (OS) in primary CNS lymphoma (PCNSL). Methods: PubMed, Embase and Cochrane Central Library were searched up to 7 June 2022. Trial-level analyses were performed by weighted linear regression of logarithmic hazard ratios for PFS and OS. Treatment arm-level analyses were performed between PFS rates and 3- or 5-year OS rates. Results: 1471 PCNSL patients in nine randomized control trials were included. PFS was associated with OS (r = 0.750; 95% CI: 0.228-0.937). Strong linear correlations existed between 1-, 2- and 3-year PFS and 3-year OS (r = 0.896-0.928), moderate or weak correlations existed between 3- to 6-month PFS and 3-year OS, 3-month to 5-year PFS and 5-year OS. Conclusion: Short-term PFS can validly substitute for long-term OS in PCNSL.

European Association of Neuro-Oncology (EANO) guidelines for treatment of primary central nervous system lymphoma (PCNSL)

The management of primary central nervous system (PCNSL) is one of the most controversial topics in neuro-oncology because of the complexity of the disease and the limited number of controlled studies available. In 2021, given recent advances and the publication of practice-changing randomized trials, the European Association of Neuro-Oncology (EANO) created a multidisciplinary task force to update the previously published evidence-based guidelines for immunocompetent adult patients with PCNSL and added a section on immunosuppressed patients. The guideline provides consensus considerations and recommendations for the treatment of PCNSL, including intraocular manifestations and specific management of the elderly. The main changes from the previous guideline include strengthened evidence for the consolidation with ASCT in first-line treatment, prospectively assessed chemotherapy combinations for both young and elderly patients, clarification of the role of rituximab even though the data remain inconclusive, of the role of new agents, and the incorporation of immunosuppressed patients and primary ocular lymphoma. The guideline should aid the clinicians in everyday practice and decision making and serve as a basis for future research in the field.

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.

Revisiting the concept of recurrence of primary CNS lymphomas after complete response to methotrexate-based therapy: Periventricular reseeding as the predominant mechanism of recurrence

Purpose

Understanding patterns of relapse for primary central nervous system lymphoma (PCNSL) may inform mechanisms of recurrence and optimal consolidation strategies. In this study, we report patterns of relapse among patients with PCNSL who achieved a complete response to high-dose methotrexate (HD-MTX)-based chemotherapy with or without consolidation radiation therapy (RT).

Methods and Materials

We conducted an institutional retrospective analysis of patients with PCNSL who received HD-MTX-based chemotherapy between November 2001 and May 2019. Relapses were characterized as in-field (within original T1 contrasted lesion), marginal (within T2 fluid-attenuated inversion recovery but not T1), local (in-field or marginal), distant brain (no overlap), or distant (distant brain, cerebrospinal fluid, vitreous or extra-axial) and further characterized with respect to periventricular location (≤10 mm of ventricles).

Results

Seventy-eight patients with PCNSL met inclusion criteria, of whom 29 (37%) underwent consolidation RT. Median progression-free survival and overall survival were 57.0 and 66.7 months, respectively. After a median follow-up of 38.9 months, a total of 32 patients (41%) experienced recurrence. Most patients (21 [65.6%]) had a periventricular failure. Surprisingly, local recurrences (n = 11) were exclusively observed within periventricular lesions, whereas distant recurrences (n = 21) were seen in both periventricular and nonperiventricular locations (P = .009). The median time to progression was shorter for locally recurrent lesions compared with distant recurrences (13.8 vs 26.1 months; P = .03).

Conclusions

After complete response to HD-MTX, few failures occurred within initial T1 contrast-enhancing lesions and many of these may have been alternatively classified as periventricular failures. These observations argue against the use of purely focal RT consolidation for patients who achieve a complete response after HD-MTX-based chemotherapy and suggest that periventricular reseeding may have a central role in PCNSL recurrence.