Significance of myc gene rearrangement and its correlation with prognosis in diffuse large B cell lymphoma

Abstract

To study the relationship between myc gene rearrangement and myc protein expression in diffuse large B cell lymphoma (DLBCL), and their correlation with prognosis. One hundred and six cases of DLBCLs with follow-up data were analyzed using interphase fluorescence in situ hybridization (FISH) technique. Immunophenotyping analysis for CD20, CD3, myc, Mum-1, CD10, bcl-6 was also performed using EnVision immunohistochemistry. The percentages of tumor cells expressing myc, Mum-1, CD10 and bcl-6 were 70.8%, 56.6%, 21.7% and 26.4%, respectively. Twenty six cases (24.5%) were of GCB type and the rest (75.5%) were of non-GCB (non germinal center) type. The myc rearrangement was identified in 13 (12.3%) of 106 cases. 13 cases showed to be of non-GCB type. There was no correlation between myc rearrangement and myc protein expression. DLBCLs (n = 13) with myc rearrangement showed significantly poorer overall survival (OS) and progression free survival (PFS), with a median OS and PFS time of 4.7 and 3.2 months, respectively (for OS and PFS, P < 0.001). Multivariate analysis using Cox proportional hazard model confirmed that myc rearrangement, ECOG performance status of 2-4, immunophenotyping subgroup and myc protein were independent factors affecting the prognosis and significantly associated with the survival. However, myc rearrangement was the strongest prognostic factor. DLBCL with myc gene rearrangement is a subgroup of non-GCB DLBCL with poor outcome. It is an independent and useful factor for prognosis in DLBCL. Expression of myc is influenced by many factors and myc rearrangement may be one of these factors.