P1194: prognostic significance of sequential 18f-fdg pet/ct during the treatment of anthracycline-containing frontline chemotherapy in peripheral t cell lymphomas

Topic: 19. Aggressive Non-Hodgkin lymphoma - Clinical Background: pite the prognostic significance of 18F-fluorodeoxyglucose (FDG)-positron emission tomography-computed tomography (PET/CT) assessment has important implications on determining the response-adapted therapy in patients with peripheral T-cell lymphomas (PTCLs), an optimal timing of the use and clinical application of PET/CT-based response are still up in the air. Aims: The aim of this study was to explore the prognostic impact of sequential 18F-FDG PET/CT analysis in patients with newly diagnosed PTCLs who treated with frontline anthracycline-based chemotherapy. Methods: One-hundred and forty-three patients with newly diagnosed PTCLs except extranodal NK/T cell lymphoma were included between February 2006 and September 2022. All patients were treated with anthracycline-based chemotherapy. Sequential 18F-FDG PET/CT were obtained at the time of diagnosis, after three cycles of chemotherapy and finally at the end of chemotherapy. Baseline total metabolic tumor volume (TMTV) was computed with the sum of SUV2.5 threshold method, and the interim PET/CT response were assessed using the five-point scale (5-PS) of Deauville criteria. Results: Baseline MTV could be calculated in 126 patients, and median TMTV was 193.9 (range 0.3-3,614.0) cm3. The cut-off value of TMTV was 457.0 cm3 (Sensitivity 45.0%, specificity 74.0%). Patients with high TMTV more than cut-off value had inferior PFS and OS than those with low TMTV (PFS, 9.8 months vs. 26.5 months, HR 1.600, 95% CI 1.010-2.671, p=0.043, Figure 1A; OS, 18.9 months vs. 71.2 months, HR 2.135, 95% CI 1.261-3.615, p=0.004, Figure 1B). Interim 18F-FDG PET/CT assessment was available in all 143 patients. Among 143 patients. When patients were categorized with three subgroups as response with grade 1, grade 2 and 3, and grade 4-5, PFS and OS showed significant difference according to interim visual assessment (PFS, 120.7 months vs. 34.1 months vs. 5.1 months, p<0.001, Figure 1C; OS, not reached vs.61.1 months vs. 12.1 months, p<0.001, Figure 1D). Summary/Conclusion: In conclusion, high baseline TMTV could indicate a poor response to anthracycline-based chemotherapy in PTCLs. Interim PET/CT response based on visual assessment could be a valuable predictive factor of disease progression and survival outcome in the anthracycline-containing treatment of PTCLs. Figure 1. Progression-free survival (A) and overall survival (B) according to the baseline total metabolic tumor volume (TMTV) using a ROC cutoff (457cm3) for TMTV. Progression-free survival (C) and overall survival (D) according to the interim 18F-FDG PET/CT Deauville score.Keywords: Peripheral T-cell lymphoma