MYC overexpression but not MYC/BCL2 double expression predicts survival in bulky mass diffuse large B-cell lymphoma patients

Purpose: The prognostic factors for diffuse large B-cell lymphoma (DLBCL) have been fully explored, but prognostic information for bulky mass DLBCL patients is limited. This study aimed to analyze the prognostic value of MYC protein expression and other biological parameters in bulky mass DLBCL patients. Methods: We defined a bulky mass as a maximum tumor diameter =7.5 cm and studied 227 patients with de novo bulky mass DLBCL. Results: In all patients with bulky mass DLBCL, the 1-year and 3-year OS rates were 72.7% and 57.1%, respectively, and the 1-year and 3-year PFS rates were 52.0% and 42.5%, respectively. The MYC overexpression group (n = 140) showed significantly worse overall survival (OS; p = 0.019) and progression-free survival (PFS; p = 0.001) than the non-MYC overexpression group (n = 87). Subgroup analyses demonstrated that the MYC overexpression group was associated with inferior OS and PFS in the subgroups with the International Prognostic Index score of 3-5 (OS: p = 0.011; PFS: p < 0.001), Ann Arbor stage 3-4 (OS: p = 0.014; PFS: p < 0.001) and GCB subtype (OS: p = 0.014; PFS: p = 0.010). Consolidation radiotherapy improved OS and PFS in patients with bulky mass DLBCL (OS: p = 0.008; PFS: p = 0.004) as well as in those with MYC overexpression (OS: p = 0.001; PFS: p = 0.001). The prognostic value of MYC overexpression was maintained in a multivariate model adjusted for the International Prognostic Index. Conclusion: MYC overexpression is a poor predictor for bulky mass DLBCL patients. Consolidation radiotherapy for residual disease after induction therapy may improve outcomes for patients with bulky mass DLBCL.