Prognostic value of ¹⁸F-FDG PET/CT tumor metabolic parameters and Ki-67 in pre-treatment diffuse large B-cell...

Diffuse large B-cell lymphoma (DLBCL) is a highly aggressive lymphoma. Rituximab-based conventional chemotherapy still leads to drug resistance or relapse in 30-40% of patients. Therefore, early identification of high-risk patients and accurate assessment of prognosis are very important for clinical decision-making. The aim of this study is to investigate the value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) of tumor metabolic, clinical and biological parameters in the prognostic risk stratification of DLBCL before treatment.

We retrospectively collected clinical data on 63 patients with newly diagnosed DLBCL admitted to Shanxi Bethune Hospital during the period from November 2016 to April 2020 who underwent ¹⁸F-FDG PET/CT prior to treatment in a cohort study. Metabolic, clinical, and biological parameters were analyzed by Cox regression. Kaplan-Meier curves of patient survival were compared by the log-rank test.

The median follow-up was 21 months. The 2-year progression-free survival (PFS) was 47.62%, and the overall survival (OS) was 53.97%. The subtype, double expression, Ann Abor stage, NCCN-IPI score, Ki-67, maximum standardized uptake value (SUV_max), bulk volume glycolysis (BVG), total lesion glycolysis (TLG), total metabolic tumor volume (TMTV) were the influencing factors for PFS and OS (P<0.050) in univariate analysis. BVG (PFS: HR =6.62, P<0.001; OS: HR =3.53, P=0.029), TLG (PFS: HR =8.56, P<0.001; OS: HR =5.20, P=0.004), TMTV (PFS: HR =12.02, P=0.001; OS: HR =5.05, P=0.033) and Ki-67 were found to be independent prognostic risk stratification parameters affecting PFS and OS by multivariate regression analysis. The 2-year PFS and OS rates for patients with high BVG (≥288.00 cm³), TLG (≥1,854.00 cm³), TMTV (≥103.00 cm³), and Ki-67 (≥85%) were 20% and 28.57%, 9.68% and 22.58%, 20.51%, and 30.77%, and 25% and 33.33%, respectively; and the 2-year PFS and OS rates for patients with low BVG (<288.00 cm³), TLG (<1,854.00 cm³), TMTV (<103.00 cm³), and Ki-67 (<85%) patients were 82.14% and 85.71%, 84.37% and 84.37%, 91.67% and 91.67%, and 61.54% and 66.67%, respectively. Patients with high BVG, TLG, TMTV, and Ki-67 had a worse 2-year PFS as well as OS rate (Ki-67: P=0.0018/P=0.0025; P<0.0001 for the rest of the groups).

Our findings suggest that BVG, TLG, TMTV, and Ki-67 are independent prognostic indicators for survival in patients with pre-treatment DLBCL, especially BVG, which is a novel prognostic indicator that has to be validated in future research.