Metabolic Tumor Volume from Baseline PET/CT Improves Stratification in the High IPI Risk Patients with Diffuse Large B‐Cell Lymphoma

Background: In the rituximab era, the international prognostic index (IPI) risk stratification was not enough to predict outcome in patients with diffuse large B cell lymphoma (DLBCL). Previous studies showed the Metabolic tumor volume（MTV） from baseline [¹⁸F]FDG PET/CT could be used to predict outcome. In this study, we evaluated the prognostic value of IPI and MTV in DLBCL patients.

Patients and methods: A total of 262 de novo DLBCL patients who were treated with the R-like chemotherapy were retrospectively analyzed in this study. The IPI and MTV were compared to the Overall Survival (OS) and Progression Free Survival (PFS).

Results: The MTV is better than TLG and SUVmax for predicting disease progression. The cutoff value of MTV was 444 cm³. Patients with high MTV showed inferior OS and PFS (p < 0.001, respectively). Although the IPI remains predictive it distinguishes only 2 risk groups, rather than the 4 groups originally described. Further analysis showed high MTV could identify a subgroup of patients with extremely inferior OS and PFS in high IPI risk patients (p = 0.0089 and p= 0.024, respectively). Multivariate analysis revealed that high MTV is a significant poor prognostic factor for both OS (HR 3.168[1.81-5.56], p <0.001) and PFS (HR 2.637 [1.51-3.71], p <0.001).

Conclusions: Our study suggests that MTV from baseline PET/CT is an important prognostic factor in DLBCL patients, allowing the identification of an inferior outcome subgroup in high-risk patients, which may help to guide treatment in clinical trial.