PROGNOSTIC SIGNIFICANCE OF SEQUENTIAL 18F‐FDG PET/CT DURING THE TREATMENT OF ANTHRACYCLINE‐CONTAINING FRONTLINE CHEMOTHERAPY IN PERIPHERAL T CELL LYMPHOMAS

Abstract

Introduction: Despite 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. 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: Between February 2006 and September 2022, 143 patients with newly diagnosed PTCLs were included. All patients were treated with 6 cycles of anthracycline-containing 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 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 the cut-off value of TMTV according to ROC analysis was 457.0 cm3 (Sensitivity 45.0%, specificity 74.0%). With a median follow-up of 52.0 months (range 3.8–153.9 months), 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; OS, 18.9 months vs. 71.2 months, HR 2.135, 95% CI 1.261–3.615, p = 0.004, Figure 1A, B). Interim 18F-FDG PET/CT assessment was available in all 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; OS, not reached vs. 61.1 months vs. 12.1 months, p < 0.001, Figure 1C, D), respectively. Among 77 patients who were assessed as grade 2 or 3 in interim PET/CT analysis, 19 patients (26.3%) turned over a remnant tumor metabolism or progressed at final PET response assessment. Moreover, the outcome of patients with interim grade 2 or 3 showed the significant differences based on the final achievement of complete metabolic response or not in PFS and OS (PFS, 59.9 months vs. 7.2 months, HR 4.754, 95% CI 2.267–9.971, p < 0.001; OS, not reached vs. 24.0 months, HR 3.706, 95% CI 1.592–8.630, p = 0.001), respectively. Keywords: aggressive T-cell non-Hodgkin lymphoma, diagnostic and prognostic biomarkers No conflicts of interests pertinent to the abstract.