Prognostic Value of Semi-Quantitative Metabolic Parameters on [18F]FDG PET/CT in Patients with Diffuse Large B-Cell Lymphoma at Diagnosis

After first-line therapy with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), 20–30% of patients with diffuse large B-cell lymphoma (DLBCL) have relapsed or refractory disease. Semi-quantitative volume parameters on [18F]Fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG PET/CT), performed at diagnosis, could represent variables with prognostic influence. We retrospectively analyzed 53 consecutive patients, treated between 2016 and 2022. Semi-quantitative metabolic parameters, assessed by the software LIFEx, included total metabolic tumor volume (TMTV), total lesion glycolysis (TLG), Dmax and DmaxVox. All cases received R-CHOP/CHOP-like regimens with curative intent. The International Metabolic Prognostic Index (IMPI) was low in 43/53 cases (81.1%). CR was achieved in 49/53 patients (92.4%); 7/53 (13.2%) relapsed after achieving a CR. For the entire cohort, 2-year PFS and OS were 84.9% and 90.6%, respectively, while 5-year PFS and OS were 65.5% and 77.6%, respectively. IPI score, B symptoms, TMTV, Dmax and DmaxVox were associated with reduced PFS in an exploratory univariate analysis. IPI score was the only variable for which we found a significant association with reduced OS. In this exploratory analysis in a small, event-limited population, we suggest the baseline, semi-quantitative metabolic parameters of PET/CT at diagnosis could contribute to defining tumor burden and to predict PFS for DLBCL patients.