Long-Term Evaluation of Combination Treatment of Single Agent HD-MTX Chemotherapy up to Three Cycles and Moderate Dose Whole Brain Irradiation for Primary CNS Lymphoma.

High-dose methotrexate (HD-MTX)-based chemotherapy in combination with whole brain radiotherapy (WBRT) has been a common therapy for primary central nervous system lymphoma (PCNSL). The aim of this study was to evaluate the survival benefit of a minimized cycle of HD-MTX monotherapy prior to WBRT. A maximum of three cycles of HD-MTX was combined with a WBRT dose of 30 Gy and an additional localized boost was administered where remnant was observed. A total of 54 patients with newly diagnosed PCNSL were enrolled in this study. The objective response rate for HD-MTX was 80% and the median overall survival was 58.4 months. Responders to HD-MTX demonstrated better survival than patients with resistance. The concentration of MTX in serum and cerebrospinal fluid was not related the chemotherapeutic response. This study demonstrated the efficacy of HD-MTX prior to WBRT and indicated that three cycles of HD-MTX monotherapy may be sufficient in combination with radiotherapy.