Clinical and Pathologic Correlation of Increased MYC Gene Copy Number in Diffuse Large B-Cell Lymphoma.

Abstract

Only a few studies have investigated the presence of increased MYC gene copy number (ICN) as a prognostic indicator in patients with diffuse large B-cell lymphoma (DLBCL), and the results have been variable. We compared overall survival in patients with ICN to MYC-negative patients and investigated the prognostic significance of increased MYC gene copy number. Two groups, those with MYC ICN (n= 33) and those with no MYC aberrations (n= 43), identified by fluorescence in-situ hybridization DNA probes for the MYC region at 8q24, were compared for survival (1-9 years), MYC immunohistochemical (IHC) protein expression, and treatment protocol. Comparison of cases of DLBCL with MYC ICN to those with no MYC aberration demonstrated no significant difference in survival (P= .58). Additionally, no difference in survival was found between patients with increased MYC protein expression (IHC MYC≥ 40%) compared to those with IHC MYC< 40% (P= .5). Comparison of Ki-67 proliferation rates, stratified into low and high groups, did not achieve statistical significance (P= .67). Patients with MYC ICN showed a slightly increased MYC protein expression (P > .05). Importantly, the majority of patients in both groups (79% of patients with ICN and 81% of patients with no MYC aberrations) were treated with rituximab-based therapies. No significant difference in survival was found between patients with DLBCL with MYC ICN and patients with no MYC aberrations (P= .58).