INCIDENCE AND RISK FACTORS FOR CENTRAL NERVOUS SYSTEM RELAPSE IN PATIENTS WITH PRIMARY MEDIASTINAL LARGE B-CELL LYMPHOMA IN THE RITUXIMAB ERA.

Central nervous system (CNS) involvement is rare in primary mediastinal large B-cell lymphoma (PMLBCL). We aimed to evaluate the incidence of CNS relapse as first treatment failure event and the effect of the induction chemotherapy regimen, CNS-IPI and other clinical and laboratory variables on the risk of CNS relapse in 564 PMLBCL patients treated with immunochemotherapy. Only 17 patients (3.0%) received CNS prophylaxis. During a 55-month median follow-up only 8 patients experienced CNS relapse as first event, always isolated. The 2-year cumulative incidence of CNS relapse (CI-CNSR) was 1.47% and remained unchanged thereafter. The CI-CNSR was not affected by the chemotherapy regimen (R-CHOP or R-da-EPOCH). None of the established IPI factors for aggressive lymphomas predicted CNS relapse in PMLBCL. The 2-year CI-CNSR in patients with vs without kidney involvement was 13.3% vs 0.96% (p<0.001); 14.3% vs 1.13% with vs without adrenal involvement (p<0.001); and 10.2% vs 0.97% with vs without either kidney or adrenal involvement. CNS-IPI was also predictive (2-year CI-CNSR in high-risk vs intermediate/low-risk: 10.37% vs 0.84%, p<0.001). However, this association may be driven mainly by kidney and/or adrenal involvement. In conclusion, in PMLBCL, CNS relapse is rare and appears to be strongly associated with kidney and/or adrenal involvement. This article is protected by copyright. All rights reserved.