¹⁸F-FDG PET Dissemination Features in Diffuse Large B-Cell Lymphoma Are Predictive of Outcome

We assessed the predictive value of new radiomic features characterizing lesion dissemination in baseline ¹⁸F-FDG PET and tested whether combining them with baseline metabolic tumor volume (MTV) could improve prediction of progression-free survival (PFS) and overall survival (OS) in diffuse large B-cell lymphoma (DLBCL) patients. <b>Methods:</b> From the LNH073B trial (NCT00498043), patients with advanced-stage DLCBL and ¹⁸F-FDG PET/CT images available for review were selected. MTV and several radiomic features, including the distance between the 2 lesions that were farthest apart (Dmax_patient), were calculated. Receiver-operating-characteristic analysis was used to determine the optimal cutoff for quantitative variables, and Kaplan-Meier survival analyses were performed. <b>Results:</b> With a median age of 46 y, 95 patients were enrolled, half of them treated with R-CHOP biweekly (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) and the other half with R-ACVBP (rituximab, doxorubicin, cyclophosphamide, vindesine, bleomycin, and prednisone), with no significant impact on outcome. Median MTV and Dmax_patient were 375 cm³ and 45 cm, respectively. The median follow-up was 44 mo. High MTV and Dmax_patient were adverse factors for PFS (<i>P</i> = 0.027 and <i>P</i> = 0.0003, respectively) and for OS (<i>P</i> = 0.0007 and <i>P</i> = 0.0095, respectively). In multivariate analysis, only Dmax_patient was significantly associated with PFS (<i>P</i> = 0.0014) whereas both factors remained significant for OS (<i>P</i> = 0.037 and <i>P</i> = 0.0029, respectively). Combining MTV (>384 cm³) and Dmax_patient (>58 cm) yielded 3 risk groups for PFS (<i>P</i> = 0.0003) and OS (<i>P</i> = 0.0011): high with 2 adverse factors (4-y PFS and OS of 50% and 53%, respectively, <i>n</i> = 18), low with no adverse factor (94% and 97%, <i>n</i> = 36), and an intermediate category with 1 adverse factor (73% and 88%, <i>n</i> = 41). <b>Conclusion:</b> Combining MTV with a parameter reflecting the tumor burden dissemination further improves DLBCL patient risk stratification at staging.