The role of pre-treatment and mid-treatment 18F-FDG PET/CT imaging in evaluating prognosis of peripheral T-cell lymphoma-not otherwise specified (PTCL-NOS)

Abstract

Background: It has been reported the prognostic value of MTV in predicting the disease prognosis of peripheral T-cell lymphoma (PTCL) through pre-treatment PET/CT imaging. However, these are limited data on pretreatment evaluation and prognosis assessments of peripheral T-cell lymphoma-not otherwise specified (PTCL-NOS). This study aimed to determine the prognostic values of pre-treatment and mid-treatment total metabolic tumor volume (MTV), total lesion glycolysis (TLG), and Deauville 5-Point Scale (D-5PS) in accessing the prognosis of PTCL-NOS. Methods: A retrospective analysis was conducted in 31 patients with pathologically diagnosed PTCL-NOS. These patients have undergone positron emission PET/CT scanning before and during chemotherapy. Follow-ups were also done to investigate the 2-year progression-free survival (PFS) and Overall Survival (OS) of these patients. During 18F-fluorodeoxyglucose (18F-FDG) PET/CT scans, the MTV and TLG were recorded. Meanwhile, △ MTV and △ TLG were calculated. Furthermore, the receiver operating characteristic (ROC) curve was employed to classify and to define the threshold values. On the other hand, the mid-chemotherapy assessment and staging of these 31 patients were done by utilizing D-5PS. Subsequently, based on the D-5PS scores obtained, these patients were grouped into two categories: a group of patients with a score of <4 and another group with ≥ 4 points. For these two groups of patients, the survival analysis was done by Kaplan–Meier analysis and a multivariate COX regression model. Moreover, Pearson’s chi-square test (χ2 test) and Spearman rank correlation coefficient were used to comparing the collected data, respectively. Results: During the 2-year follow-up period, 15 out of the 31 patients experienced disease progression. The optimal threshold values for both baseline MTV and TLG were 158.16 cm3 and 677.40.Additionally, the difference in 2-year PFS between the progressive and non-progressive groups was statistically significant (χ2= 8.193 , P= 0.004 < 0.05 ; χ2= 8.872 , P= 0.003 < 0.05), significant between-group difference was detected for MTV and for TLG (χ2= 6.494 , P= 0.011 < 0.05 ; χ2= 4.687 , P= 0.03 < 0.05). On the other hand, when these patients were classified into two groups according to the mid-chemotherapy Deauville score of <4 and ≥ 4, the statistical difference of 2-year PFS between these two groups was significant, too (χ2= 14.966 , P= 0.001 < 0.05),but there is no significant between-group difference in OS (χ2= 3.337 , P= 0.068 < 0.05). COX analysis revealed that D-5PS are the independent factors influencing PFS, while MTV is the independent influencing factor of OS. Conclusion: The baseline total MTV obtained by PET/CT scanning, and D-5PS are crucial prognostic factors in evaluating the prognosis of PTCL-NOS.