Abstract
Primary central nervous system lymphoma (PCNSL) is a rare topographic variant of diffuse large B-cell lymphoma (DLBCL). While prognostic scales are useful in clinical trials, no dynamic prognostic marker is available in this disease. We report here the prognostic value of early metabolic response by 18F-FDG PET scanner (PET) in 25 newly diagnosed immunocompetent PCNSL patients. Induction treatment consisted of four cycles of Rituximab, Methotrexate and Temozolamide (RMT). Based on patient's general condition, consolidation by high-dose Etoposide and Aracytine was given to responding patients. Brain MRI and PET were performed at diagnosis, after two and four cycles of RMT, and after treatment completion. Two-year progression-free (PFS) and overall survival (OS) were 62% and 74%, respectively for the whole cohort. Best responses after RMT induction were 18 (72%) complete response (CR)/CR undetermined (CRu), 4 (16%) partial response, 1 (4%) progressive disease and 2 (8%) stable disease. Response evaluation was concordant between MRI and PET at the end of induction therapy. Nineteen patients (76%) had a negative PET2. Predictive positive and negative values of PET2 on end-of-treatment (ETR) CR were 66.67% and 94.74%, respectively. We observed a significant association between PET2 negativity and ETR (p = 0.001) and longer PFS (p = 0.02), while having no impact on OS (p = 0.32). Two years PFS was 72% and 33% for PET2– and PET2+ patients, respectively (p < 0.02). PET2 evaluation may help to early define a subgroup of CR PCNSL patients with a favorable outcome.
Highlights
Primary central nervous system lymphoma (PCNSL) is a rare central nervous system (CNS)localized extra nodal variant of diffuse large B-cell lymphoma
Recent advances highlighted that long-term remission and even cure could be achieved for a significant proportion of PCNSL patients using Methotrexate-based chemotherapy regimens and intensive consolidation strategies [2]
The initial positron emission tomography (PET) excluded an extra-cerebral localization of lymphoma in all patients
Summary
Primary central nervous system lymphoma (PCNSL) is a rare central nervous system (CNS)localized extra nodal variant of diffuse large B-cell lymphoma. Recent advances highlighted that long-term remission and even cure could be achieved for a significant proportion of PCNSL patients using Methotrexate-based chemotherapy regimens and intensive consolidation strategies [2]. Current frontline management recommendations of PCNSL patients mostly rest on the results of prospective phase 2 trials and involve chemotherapy regimens using 3–8 g/m2 methotrexate for 4 to 8 infusions, with an overall response rate of 60–80% [3,4,5,6]. The main PCNSL prognostic factors identified so far are age and performance status, both integrated into the widely used International Extranodal Lymphoma Study Group experience (IESLG) and Memorial Sloan-Kettering (MSK) prognostic scores [10, 11]. We assessed the impact of early metabolic response evaluated by PET after two cycles of the Rituximab, Methotrexate and Temozolomide (RMT) regimen (PET2) in 25 consecutive newly-diagnosed immunocompetent PCNSL patients
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