OUTCOME OF PATIENTS WITH NEWLY DIAGNOSED PRIMARY CNS LYMPHOMA AFTER HIGH‐DOSE METHOTREXATE FOLLOWED BY CONSOLIDATION WHOLE‐BRAIN RADIOTHERAPY AND CYTARABINE

Abstract

Background Addition of cytarabine to high-dose methotrexate (HD-MTX) chemotherapy improves outcome of primary CNS lymphoma (PCNSL); however, the combination therapy increases toxicity. Sequential chemotherapy and cranial radiation may decrease toxicity without altering efficacy. Methods This was a single-center, retrospective cohort study of consecutive newly diagnosed immunocompetent PCNSL patients treated with HD-MTX (5 cycles of 3 g/m2 every 2 weeks) followed by consolidation whole-brain radiotherapy (WBRT) and cytarabine (2 cycles of 3 g/m2/d for 2 days every 3 weeks) from January 2013 to December 2020. Initial WBRT before HD-MTX was allowed in patients with significant disability or brain edema at presentation. Primary outcome was progression-free survival (PFS). Key secondary outcomes were response rate, treatment-related toxicity, and overall survival (OS). Results Of 41 patients, 25 patients had a complete response (CR) and ten patients had a partial response, inferring an overall response rate (ORR) of 85.4% and a CR rate of 60.9%. More than 90% of patients were able to tolerate and complete the HD-MTX. The incidence of ≥ grade 3 hematologic and non-hematologic toxicities were 4.8% and 17.1%, respectively. Treatment-related mortality rate was 2.4%. There was no difference in toxicity between patients with age < 60 and ≥ 60 years. At the median follow-up duration of 39.8 months, the median PFS was 35.2 months (95% CI 12.4–69.3) and median OS was 46.5 months (95% CI 21.8–NR). Conclusion High-dose methotrexate followed by consolidation whole-brain radiotherapy and cytarabine has acceptable efficacy, great tolerability, and low toxicity in newly diagnosed PCNSL patients.