Tumour necrosis as assessed with ¹⁸F-FDG PET is a potential prognostic marker in diffuse large B cell lymphoma independent of MYC rearrangements

Objectives: MYC gene rearrangements in diffuse large B cell lymphomas (DLBCLs) result in high proliferation rates and are associated with a poor prognosis. Strong proliferation is associated with high metabolic demand and tumour necrosis. The aim of this study was to investigate differences in the presence of necrosis and semiquantitative ¹⁸F-FDG PET metrics between DLBCL cases with or without a MYC rearrangement. The prognostic impact of necrosis and semiquantitative ¹⁸F-FDG PET parameters was investigated in an explorative survival analysis.

Methods: Fluorescence in situ hybridisation analysis for MYC rearrangements, visual assesment, semiquantitative analysis of ¹⁸F-FDG PET scans and patient survival analysis were performed in 61 DLBCL patients, treated at a single referral hospital between 2008 and 2015.

Results: Of 61 tumours, 21 (34%) had a MYC rearrangement (MYC⁺). MYC status was neither associated with the presence of necrosis on ¹⁸F-FDG PET scans (necrosis^PET; p = 1.0) nor associated with the investigated semiquantitative parameters maximum standard uptake value (SUV_max; p = 0.43), single highest SUV_max (p = 0.49), metabolic active tumour volume (MATV; p = 0.68) or total lesion glycolysis (TLG; p = 0.62). A multivariate patient survival analysis of the entire cohort showed necrosis^PET as an independent prognostic marker for disease-specific survival (DSS) (HR = 13.9; 95% CI 3.0-65; p = 0.001).

Conclusions: MYC rearrangements in DLBCL have no influence on the visual parameter necrosis^PET or the semi-quantiative parameters SUV_max, MATV and TLG. Irrespective of MYC rearrangements, necrosis^PET is an independent, adverse prognostic factor for DSS.

Key points: • Retrospective analysis indicates that MYC rearrangement is not associated with necrosis on ¹⁸ F-FDG PET (necrosis ^PET ) scans or semiquantitative ¹⁸ F-FDG PET parameters. • Necrosis ^PET is a potential independent adverse prognostic factor for disease-specific survival in patients with DLBCL and is not influenced by the presence of MYC rearrangements.