Low Rate of Central Nervous System Relapse of Diffuse Large B-Cell Lymphoma Despite Limited Use of Intrathecal Prophylaxis.

Background: The incidence of central nervous system (CNS) relapse in diffuse large B-cell lymphoma (DLBCL) varies, and the optimum strategy of CNS prophylaxis remains to be defined. We aimed to evaluate the incidence of CNS relapse in DLBCL patients and the role of CNS prophylaxis.

Methods: Data on patients diagnosed with DLBCL at our institution from January 2011 to June 2019 were retrospectively collected from the charts and computerized hospital information system for patient demographics, lymphoma stage at diagnosis, CNS international prognostic index (IPI) scores, extra-nodal sites, chemotherapy type, CNS prophylaxis, and CNS relapse. CNS prophylaxis comprised intrathecal (IT) chemotherapy and was administered based on the presence of high-risk features. Patients with primary CNS lymphoma and CNS involvement at diagnosis were excluded.

Results: Of 101 patients, 58 (57.5%) were males with a median age of 56 (range: 16 - 87) years. Ann Arbor stages of I - IV were confirmed in nine, 21, 17, and 50 patients, respectively. The lung was the most common extranodal site involved (27, 26.7%). Twenty-five (24.75%) patients had a high-risk CNS-IPI score. Ninety-three percent of patients received R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy. Sixteen patients received CNS prophylaxis as IT methotrexate (± cytarabine and hydrocortisone). Despite high-risk CNS-IPI scores, nine (36%) patients did not receive CNS prophylaxis. After a median follow-up of 36 (range: 4 - 114) months, two patients with high-risk CNS-IPI score developed CNS relapse and died shortly.

Conclusions: CNS relapse of DLBCL was uncommon in this patient population. Low incidence of CNS relapse despite limited use of IT prophylaxis may suggest adequacy of IT prophylaxis in these patients.