Initial radiographic response predicts favorable outcome to chemotherapy in primary CNS lymphoma

Objective: The identification of prognostic factors in primary CNS lymphoma (PCNSL) is useful for treatment stratification in randomized trials and for decision making in the individual patient. Prognostic factors in PCNSL are age and performance status and possibly others. To evaluate the prognostic impact of tumor response to initial systemic and intraventricular chemotherapy cycles during ongoing treatment as assessed by magnetic resonance imaging (MRI).

Patients and methods: From 09/1995 to 12/2002, 88 patients with PCNSL were enrolled in a pilot/phase II study evaluating MTX-based high-dose chemotherapy without radiotherapy (“Bonn-Protocol“). MRI-scans were performed after two and after six courses of chemotherapy and radiographic response was assessed according to the Macdonald criteria. Overall survival (OS) and time to treatment failure (TTF) were measured. Median follow-up is 42 months (range: one to 124 months).

Results: Patients achieving a complete radiographic response already after two courses of chemotherapy (n=18) had a significantly longer median OS (not reached) and median TTF (not reached) than patients with complete response after termination of treatment (n=24) (OS: 55 months; TTF: 32 months) (p=0,01).

Conclusion: Early tumor response assessed by MRI already in the early stage of treatment was shown to be a highly predictive prognostic factor for both OS and TTF in patients with PCNSL treated with combined systemic and intraventricular chemotherapy. Patients without such an early response to chemotherapy possibly should be switched to alternative treatment strategies.