Bcl‐6 predicts improved prognosis in primary central nervous system lymphoma

BACKGROUND: In systemic non-Hodgkin lymphoma (NHL), tumors that resemble germinal center B-cells are less aggressive than tumors that resemble postgerminal center B-cells. However, the value of B-cell differentiation markers in primary central nervous system lymphoma (PCNSL) is less clear. The objectives of this study were to characterize the immunophenotypes of PCNSL samples and to determine their utility in predicting clinical outcomes. METHODS: The immunohistochemical staining profile of PCNSL was determined from 66 immunocompetent patients. Then, the authors evaluated whether the expression of these proteins was associated with progression-free or overall survival. RESULTS: Only 8% of PCNSL samples were positive for the cluster designation (CD) germinal center marker CD10. Another germinal center marker, bcl-6, was positive in 47% of samples. Ninety-four percent of samples expressed significant levels of the postgerminal center marker melanoma-associated antigen (MUM-1). In univariate analyses, only bcl-6 staining had a significant effect on progression-free survival (median, 20.5 months in bcl-6-positive patients vs 10.1 months in bcl-6-negative patients; P = .02). There was a nonsignificant trend toward improved overall survival in patients who had bcl-6 expressing tumors. Older age and poorer performance status, as observed previously, were associated with reduced survival. CONCLUSIONS: Bcl-6 expression was associated with a better prognosis in patients with PCNSL.