Brain glucose metabolism in diffuse large B-cell lymphoma patients as assessed with FDG-PET: Impact on outcome and chemotherapy effects

Background: There is a lack of data on the effect of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) therapy on brain glucose metabolism of diffuse large B-cell lymphoma (DLBCL) patients, as measured by 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET). Moreover, the prognostic value of brain glucose metabolism measurements is currently unknown. Purpose: To investigate the use of FDG-PET for measurement of brain glucose metabolism in R-CHOP-treated DLBCL patients, and to assess its prognostic value. Material and Methods: This retrospective study included DLBCL patients who underwent FDG-PET including the brain. FDG-PET metabolic volume products (MVPs) of the entire brain, cerebral cortex, basal ganglia, and cerebellum were measured, before and after R-CHOP therapy. Whole-body total lesion glycolysis (TLG) was also measured. Results: Thirty-eight patients were included, of whom 18 had an appropriate end-of-treatment FDG-PET scan. There were no significant differences (P>0.199) between pre-and post-treatment brain glucose metabolism metrics. Low basal ganglia MVP was associated with a significantly worse progression-free survival (PFS) and overall survival (OS) (P0.020 and P0.032), and low cerebellar MVP was associated with a significantly worse OS (P0.034). There were nonsignificant very weak correlations between pretreatment brain glucose metabolism metrics and TLG. In the multivariate Cox regression, only the National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI) remained an independent predictor of PFS (hazard ratio 3.787, P0.007) and OS (hazard ratio 2.903, P0.0345). Conclusion: Brain glucose metabolism was not affected by R-CHOP therapy. Low pretreatment brain glucose metabolism was associated with a worse outcome, but did not surpass the predictive value of the NCCN-IPI.