Veterans with diffuse large B-cell lymphoma (DLBCL) who were designated as intermediate- and high-risk for central nervous system (CNS) relapse experienced fewer instances of relapse than in previous studies, leading researchers to conclude the validated risk model may not be adequately accurate. Findings were presented at the 63rd ASH Annual Meeting & Exposition.

The authors sought to characterize veteran patients with DLBCL who experienced CNS relapse, as well as to validate risk stratification using the Central Nervous System International Prognostic Index (CNS–IPI).

“Around 2% to 5% of patients with [DLBCL] will experience [CNS] relapse resulting in a poor prognosis,” researchers noted. “CNS prophylaxis is recommended for those with high-risk CNS-IPI scores; however, the role of CNS prophylaxis has been called into question given recent large datasets showing no impact on CNS relapse.”

A retrospective chart review was conducted involving 3287 patients treated for lymphoma in Veterans Health Administration facilities. Researchers assessed baseline patient and disease characteristics, additional risk factors for CNS relapse at the time of diagnosis, response to first-line treatment, and other factors.

Of 1621 patients that met inclusion criteria, 81% had ECOG scores of 0-2, 73% received rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone chemotherapy, and 52% were designated as high-risk for CNS relapse by the CNS–IPI.

Key findings related to risk classification included:

• 12%, 36%, and 52% of patients in the sample were classified as low-, intermediate-, and high-risk, respectively;
• the low-risk group showed a 1% rate of CNS relapse (95% CI: 0%-2.4%);
• the intermediate-risk group showed a 2.4% rate of CNS relapse (CI: 1.2%-3.7%);
• the high-risk group showed a 2.4% rate of CNS relapse (CI: 1.3%-3.4%); and
• there was no statistically significant difference of risk across groups (P=.3).

Additionally, more than 90% of patients in the high-risk group did not receive CNS prophylaxis, and only 3 of 36 patients who experienced CNS relapse were given prophylaxis at baseline. Three-fourths of patients with CNS relapse achieved complete response with initial treatment.

When researchers compared intermediate- and high-risk groups classifed by CNS–IPI score, they found no significant differences “based on type of CNS relapse, type of CNS prophylaxis used, response to first-line therapy, median time to relapse, median survival time, or median time from relapse to death.”

“Although there is published data demonstrating [cell of origin] and [high-grade B-cell lymphomas] as contributing factors to CNS relapse, our data did not show any statistically significant difference in relapse rates,” authors concluded. “Our data suggests the CNS-IPI may not identify patients at risk for CNS relapse with adequate accuracy.”

Reference:
Horowitz AM, Williams MH, Williams RA, et al. Characteristics of patients with central nervous system relapse in veterans with diffuse large b-cell lymphoma within the Veterans Health Administration. Poster presented at: 63rd ASH Annual Meeting & Exposition; December 11-14, 2021: Atlanta, GA.