Efficacy and Safety of Various Treatment Regimens for Primary CNS Lymphoma: Results of a Retrospective Study Based on the Data from Nine Saint Petersburg Medical Institutions

BACKGROUND. In the Russian Federation, systematic evidence of treatment outcomes and prognosis evaluation in primary CNS lymphoma (PCNSL) patients is currently unavailable. AIM. To study the clinical and epidemiological characteristics as well as current medical practice and the first-line therapy outcomes in PCNSL patients. MATERIALS & METHODS. The study enrolled 127 adults with histologically verified PCNSL diagnosis treated from 2010 to 2024 at nine medical institutions in Saint Petersburg. Absolute majority (n = 119; 94 %) of them received various regimens of chemo- and/or immunochemotherapy (ICT). High-dose methotrexate (HD-МТХ) protocols were administered in 103 (87 %) cases, 86 % (n = 101) of PCNSL patients received rituximab. RESULTS. Response assessment was analyzed in 111 (87 %) patients. Objective response (OR) to the first-line therapy was 72 % (n = 80) including complete remissions in 38 (34 %) patients. With the follow-up of 12 months (range 0.4–151.1 months), the 2-year overall survival (OS) was 43 % (95 % confidence interval [95% CI] 34–54 %), and the 2-year event-free survival (EFS) was 30 % (95% CI 22–40 %). Prognostic factors included ECOG status and HD-МТХ administration. After ICT, 28 (38 %) patients with OR received radiation or high-dose therapy with autologous hematopoietic stem cell transplantation as consolidation treatment. Consolidation stage, irrespective of the chosen option, was associated with better rates of long-term survival: the 2-year OS was 78 % (95% CI 62–100 %), the 2-year EFS was 59 % (95% CI 41–84 %). CONCLUSION. The clinical profile of PCNSL patients, as revealed in this study, is generally consistent with published literature. Most patients received the treatment regimens in accordance with the international guidelines, however, in a part of them, suboptimal treatment was used. The best rates of long-term survival were reported in patients who achieved OR and subsequently received consolidation therapy.