Metabolic tumor burden on baseline 18 F-FDG PET/CT improves risk stratification in pediatric patients with mature B-cell lymphoma Abstract Purpose In order to better identify patients most at risk of treatment failure and disease progression in pediatric mature B-cell non-Hodgkin lymphoma (B-NHL), the prognostic role of metabolic tumor burden measured on baseline 18F-FDG PET/CT scan, including total metabolic tumor volume (TMTV) and total lesion glycolysis (TLG), was investigated. Methods Pretreatment 18F-FDG PET/CT scans from 46 consecutive pediatric patients (median age 7 years; range 2–18 years) with newly diagnosed B-NHL were retrospectively analyzed. Clinicopathological parameters and imaging characteristics, including TMTV, TLG, and bone marrow (BM) involvement detected by PET/CT were compared to predict progression-free survival (PFS) and overall survival (OS). Results The median follow-up time was 31 months. Areas under the curve of TMTV and TLG to predict events were 0.820 and 0.816, respectively. The 2-year PFS and OS were 29% and 43% in 7 patients with high TLG (> 5797 g) vs. 93% and 96% in those with low TLG (P < 0.001). High TMTV (> 524 cm3) was present in ten patients and predicted a significantly inferior outcome (PFS: 50% vs. 92%, P = 0.001; OS: 60% vs. 96%, P = 0.002). In multivariate analysis, TMTV and TLG outperformed other clinicopathological factors, including serum lactate dehydrogenase and BM involvement on biopsy, and remained the most robust predictors of survival. Furthermore, TLG sub-stratified patients with distinct outcomes efficiently within high- or intermediate-risk groups, with the negative predictive value of 100% and 92% and the positive predictive value of 100% and 50% for high-risk and intermediate-risk patients, respectively. On the other hand, BM involvement identified only by PET demonstrated an inferior prognostic value in comparison with BM biopsy. Conclusions Baseline TMTV and TLG are both strong independent prognostic factors for pediatric B-NHL and provide a potential approach to aid in risk sub-stratification, especially in patients with high-risk disease.