Evaluating early response assessment in extranodal natural killer/T-cell lymphoma by analyzing ΔSUVlbm between baseline and interim 18 F-FDG PET/CT scans

To determine the optimal variation in SUVlbm via ¹⁸F-FDG PET/CT imaging between the baseline and interim stages, and assess early response among patients with extranodal natural killer/T-cell lymphoma (ENKTCL) of 5-DS score ≥ 4, 20 patients after four cycles of chemotherapy were retrospectively enrolled and received re-biopsy targeting PET-positive residual masses. The optimal cutoff value for evaluating early response assessment was 66.75% for ΔSUVlbm%, with the area under curve of 0.985. All patients with a 5-DS score of 4 exhibited negative results upon re-biopsy. During follow-up, the median PFS of patients characterized by ΔSUVlbm% ≥66.75% and <66.75% were unreached and 10 months, respectively. Utilizing ΔSUVlbm% between baseline and interim ¹⁸F-FDG PET/CT scans can effectively identify a subset of patients who were visually analyzed as false positives(5-DS ≥ 4), which was confirmed by interim biopsy results, thus serving as a crucial indicator for early assessment of treatment outcomes in patients with ENKTCL.