Expression and prognostic significance of differentiation markers in primary CNS lymphoma (PCNSL)

Abstract

e13028 Background: BCL-6 expression has been reported to be associated with a better prognosis in PCNSL. However, significant differences of B-cell lymphoma subtypes exist in different geographic regions. The objectives of this study were to characterize the immunophenotypes of PCNSL in Japan and to determine their utility in predicting clinical outcomes. Methods: Immunostaining for CD5, CD10, BCL-6, and MUM-1 was done to determine the profile of diffuse large B-cell lymphoma of PCNSL from 27 immunocompetent patients in Japan. Then, the authors evaluated whether clinical and immunophenotypic markers were associated with progression-free or overall survival. Results: Germinal center B-cell (GCB) marker CD10 was positive in 22% of PCNSL samples, while another GCB marker BCL-6 was positive in 48% of samples. Post-GCB marker MUM-1 was positive in 81% of samples. Poor prognostic marker of systemic B-cell lymphoma CD5 was expressed in 15% of samples. In univariate analyses, only BCL-6 expression had a significant effect on progression-free survival (median, 6.1 months in BCL-6-positive patients versus 15.6 months in BCL-6-negative patients; p = 0.037). Patients with BCL-6 expression had a trend towards longer overall survival but nonsignificant. GCB subgroup (CD10-positive or CD10-negative/BCL-6-positive/MUM-1-negative) was not significantly associated with favorable survival. Conclusions: BCL-6 expression is associated with a poor prognosis in patients with PCNSL. The discrepancy between the reports from other groups and our results is potentially due to the racial, geographic or immunophenotypic differences of PCNSL. No significant financial relationships to disclose.