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)

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 F-18-fluorodeoxyglucose (F-18-FDG) PET/CT scans, the MTV and TLG were recorded. Meanwhile, Delta MTV and Delta 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 (chi(2) 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 cm(3) and 677.40.Additionally, the difference in 2-year PFS between the progressive and non-progressive groups was statistically significant (chi(2) = 8.193, P = 0.004 < 0.05; chi(2) = 8.872, P = 0.003 < 0.05), significant between-group difference was detected for MTV and for TLG (chi(2) = 6.494, P = 0.011 < 0.05; chi(2) = 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 (chi(2) = 14.966, P = 0.001 < 0.05),but there is no significant between-group difference in OS (chi(2) = 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.