Long-Term Disease Control in Patients with Primary Central Nervous System Lymphoma

Objectives: A pilot phase II trial was performed to evaluate response rate, response duration, overall survival, and toxicity in primary central nervous system lymphoma (PCNSL) after systemic and intraventricular chemotherapy with deferred radiotherapy. Patients and Methods: From 09/1995 to 12/2002, 65 patients with PCNSL (median age 62 years) were enrolled into a pilot/phase II study evaluating chemotherapy without radiotherapy. A high-dose methotrexate (MTX) (cycles 1,2,4,5) and cytarabine (ara-C) (cycles 3,6) based systemic therapy (including dexamethasone, vinca-alkaloids, ifosfamide and cyclophosphamide) was combined with intraventricular MTX, prednisolone and ara-C. Primary endpoint was time to treatment failure (TTF), secondary endpoints were response, overall survival, response duration, 5-year-survival fraction and (neuro)toxicity. Results: 34 patients were male, 31 female. Sixty-one of 65 patients were evaluable for response. Of these, 37 (61%) achieved a complete response (CR), 6 (10%) complete response/unconfirmed, and 12 (20%) progressed under therapy. Overall response rate was 71% for all patients and 86% for patients younger than 61 years. Six (9%) out of 65 patients died due to treatment-related complications. Follow-up time is 78 to 151 months in surviving patients (median 100 months). Kaplan Meier estimates for median time to treatment failure (TTF), median overall survival and median response duration are 22 months, 54 months and 37 months, respectively. For patients aged 60 years or older, the respective numbers were 7 months, 34 months and 30 months; in patients younger than 60 years, the Kaplan Meier estimate for TTF is 49 months, median overall survival and median response duration have not yet been reached. The 5-year survival fraction is 72% in patients < 60 years and 24% in older patients. Systemic toxicity was mainly hematologic. Ommaya reservoir infection occurred in 19% of the patients. At present, 17/30 (57%) of younger and 4/35 (9%) elderly patients are still alive. Only 5/30 (17%) of younger, but 19/35 (54%) of elderly patients received radiation salvage therapy at relapse. In 2/65 (3%), secondary cancers developed. In the subgroup of patients with long-term survival (n=17/30 under 61 years), 12 had an ongoing response, 1 an isolated CNS relapse (resolved by radiation), 1 an isolated ocular relapse (resolved by ocular radiation) and 3 a pure systemic relapse without CNS involvement (all resolved by systemic chemotherapy). Eleven of these 17 patients could be investigated by comprehensive neuropsychological testing, which revealed normal cognitive function in all of them. Conclusions: Primary chemotherapy based on high-dose MTX and ara-C is highly efficient in PCNSL. A substantial fraction of patients < 60 years can obviously be cured with this regimen.