Abstract Topic: 19. Aggressive Non-Hodgkin lymphoma - Clinical
Background: The prognosis of peripheral T-cell lymphoma (PTCL) is generally worse than that of non-Hodgkin aggressive B-cell lymphoma (BCL), and its prognostic stratification according to the International Prognostic Index (IPI) is still unsatisfactory. Recently, metabolic and volumetric tumour assessments based on PET-CT data, including metabolic heterogeneity (MH) and total lesion glycolysis (TLG), have been examined mainly in BCL; however, data on the prognostic utility of these radiomics are lacking in PTCL patients.
Aims: To investigate prognostic value of MH and TLG and its combination model in patients with PTCL.
Methods: We retrospectively analysed consecutive patients with newly diagnosed PTCL between 2006 and 2022, with available PET-CT data, who received chemotherapy with curative intent. Due to distinct clinical outcomes, ALK-positive anaplastic large cell lymphoma (ALCL), adult T-cell lymphoma/leukaemia, and extranodal NK/T-cell lymphoma were excluded. TLG was calculated by multiplying the metabolic tumour volume (MTV), which is defined as the total volume of the lymphoma lesion with a standardised uptake value (SUV) of ≥4 as the absolute threshold, by the mean SUV. MH represents the heterogeneity of 18F-fluorodeoxyglucose accumulation in lesions with a maximum SUV (SUVmax). The area under the curve (AUC) of the cumulative SUV-volume histogram of the SUVmax lesion was calculated, and its inversion was estimated to be MH. All PET/CT analyses were conducted using the open-source software Metavol (Hokkaido University, Sapporo, Japan).
Results: A total of 96 patients were included, of whom 50 (52.1%), 43 (44.8%), and 3 (3.1%) had PTCL, not otherwise specified (PTCL-NOS), angioimmunoblastic T-cell lymphoma, and ALK-negative ALCL, respectively. The median age was 74 years (interquartile range [IQR] 66-80). Thirty-three (34.3%) patients were categorised as having a high-risk IPI.
The median TLG and MH were 1072 (IQR: 321-2848) and 0.5 (IQR: 0.44-0.61), respectively. Receiver operating curve analysis showed that the optimal cut-off values for predicting 2-year OS and PFS were 1050 for TLG and 0.45 for MH.TLG and MH were moderately correlated (R=0.49, P<0.001). The 2-year OS and PFS rates were significantly lower in the high TLG group than in the low TLG group (2-year OS, 35% vs. 76%, P=0.001; 2-year PFS, 26% vs. 52%, P=0.02). Similarly, patients with low MH had a significantly poorer outcome than those without low MH (2-year OS 31% vs. 65%, P=0.002; 2-year PFS 25% vs. 44%, P=0.042). In the multivariate analysis, both high TLG and low MH significantly predicted 2-year OS (high TLG, hazard ratio [HR], 3.58; 95% confidence interval [CI] 1.71-7.48, P=0.001; low MH, HR 2.02, 95% CI 1.07-3.82, P=0.029) and 2-year PFS (high TLG, HR 2.2, 95% CI 1.27-3.85, P=0.005; low MH, HR 1.74, 95% CI 1.27-3.03, P=0.049).
Finally, we constructed a new prognostic model combining TLG and MH status. Patients were categorised into favourable (low TLG and high MH), intermediate (high TLG or low MH), and poor (high TLG and low MH) groups. The 2-year OS (Figure 1) and PFS rates were clearly discriminated between the three groups (2-year OS: 78% vs. 53% vs. 19%, P<0.001; 2-year PFS: 54% vs. 33% vs. 19%, P=0.014).
Summary/Conclusion: We demonstrated that high TLG and low MH had an independent significant prognostic value and improved the stratification of patients with PTCL using the combination model.
Keywords: Peripheral T-cell lymphoma, PET