Comparison of Altered Fractionation and Conventional Radiotherapy for Primary Central Nervous System Lymphoma

Abstract

Purpose: To assess the treatment outcomes of primary central nervous lymphoma (PCNSL) treated with different radiotherapy (RT) fractionation strategies (conventional fractionation vs. altered fractionated radiotherapy) with or without systemic chemotherapy. Materials and Methods: Between January 1990 and December 2004, 44 patients with PCNSL (pathological or clinical) treated with curative radiotherapy at Taipei Veterans General Hospital were reviewed. There were 29 males and 15 females, with a median age of 64 (range, 21-80). Patients were retrospectively classified into 4 groups: 1) conventional fractionated radiotherapy alone (n=15); 2) combined conventional fractionated radiotherapy with chemotherapy (n=5); 3) altered fractionated radiotherapy (1.2-1.5 Gy per fraction, twice daily) alone (n=17); and 4) altered fractionated radiotherapy with chemotherapy (n=7). All chemotherapy, mostly (n=10) methotrexate (MTX) based regimens, were given before radiotherapy. Overall survival (OS) and progression-free survival (PFS) were estimated using Kaplan-Meier method and subgroups were compared with log-rank test. Results: The median follow-up duration was 24.3 months (range, 2.7-83.1 months). Of the evaluable 39 patients, 32 patients (82%) obtained complete response and 5 patients (13%) had partial response. The median PFS was 18.9 months (95% confidence interval [CI], 10-27) with estimated 1-, 2- and 5-year PFS of 61%, 40% and 10%, respectively. The median OS was 25.8 months (95% CI, 16-36) with estimated 1-, 2- and 5-year survival rate of 75%, 54% and 15%, respectively. There was no significant difference in the OS and PFS between groups using conventional RT and altered fractionated RT regardless of chemotherapy (p=0.28 and 0.14, respectively). Age, Karnofsky performance status (KPS) and administration of chemotherapy were important prognostic factors in univariate analysis, but only age at diagnosis remained significant in multivariate model. Median survival was 35.9 months in patients younger than 64 and only 18.9 months in those aged 64 or older (p= 0.011). Patients with KPS ≥70 had a median survival of 32.2 months, which was longer than 13.1 months of patients with KPS ＜ 70 (p= 0.016). Conclusions: Altered fractionated radiotherapy is not beneficial in improving survivals of PCNSL. Age and performance status are most important prognostic predictors in PCNSL and should be taken into account in the selection of treatment modalities.