[Comparative Study of Baseline ¹⁸F-FDG PET/CT and Circulating Tumor DNA in Prognostic Assessment of Diffuse Large...

To analyze the correlation between baseline ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) and circulating tumor DNA (ctDNA) parameters in diffuse large B-cell lymphoma (DLBCL) and compare the value of the two methods in the prognosis assessment of DLBCL.

A total of 50 DLBCL patients confirmed by pathology, including 26 males and 24 females, with a median age of 55.5(43.5, 64.0) years from August 2018 to April 2021 were retrospectively analyzed. PET/CT parameters, including maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), total lesion glycolysis (TLG), ctDNA parameters, including mutation number, mutation gene number, mean variant allele frequency (meanVAF), and clinical data of patients were collected. The relationship between PET/CT, ctDNA parameters and patient clinical features was analyzed, as well as the correlation between PET/CT and ctDNA parameters. The diagnostic efficacy of PET/CT and ctDNA parameters was compared. Patients were followed up for 36-69 months. Progression-free survival (PFS) was calculated, and survival analysis was performed.

PET/CT parameters all had good correlation with ctDNA parameters, among which MTV was moderately correlated with mutation number, mutation gene number, and meanVAF (r_s=0.72, 0.64, 0.71), TLG was strongly correlated with mutation number (r_s=0.83) and moderately correlated with mutation gene number and mean VAF (r_s=0.72, 0.79), while SUVmax was weakly correlated with mutation number, mutation gene number and meanVAF (r_s=0.47, 0.46, 0.47). PET/CT parameters and ctDNA parameters showed no statistically significant differences in predicting the prognosis of DLBCL and area under the curve (AUC) of receiver operating characteristic (ROC) (P >0.05). However, the specificity of MTV and TLG in predicting prognosis of 1-, 2- and 3-year PFS was better than that of meanVAF (all P < 0.05), while the sensitivity of meanVAF in predicting prognosis of 1-, 2- and 3-year PFS was better than that of MTV (all P < 0.05). The optimal cut-off values of SUVmax, MTV, TLG, mutation number, mutation gene number and meanVAF in predicting tumor progression were obtained using ROC curve analysis. Patients were divided into high and low expression groups according to the cut-off values and survival analysis was performed. The results of survival analysis showed that there were statistically significant differences in PFS between the high and low expression groups (all P < 0.05).

Baseline ¹⁸F-FDG PET/CT and ctDNA parameters can both predict the prognosis of DLBCL, and are equally valuable in the evaluation of DLBCL prognosis.