Prognostic Value of Interim [ ¹⁸ F]FDG PET in Large B-Cell Lymphoma: A Systematic Review and Meta-analysis with a Particular Focus on Interim Deauville Score 5 Disease

Our rationale was to investigate the potential of interim [¹⁸F]FDG PET (iPET) in predicting large B-cell lymphoma (LBCL) patients' outcomes, including the end-of-treatment response, progression-free survival (PFS), and overall survival (OS). <b>Methods:</b> A systematic search was conducted on the 3 main medical literature databases until January 8, 2025. Published original articles that evaluated iPET for prognosticating LBCL patients and provided crude data for meta-analytic calculations were considered eligible. The hierarchic method was used to pool the random-effect model's end-of-treatment prediction performance measures of sensitivity, specificity, positive likelihood ratio (LR), and negative LR. The bivariate model was used to determine the corresponding 95% CI. Furthermore, PFS and OS were pooled across studies, including survival proportions and hazard ratios (HRs). All analyses were conducted using STATA 16 software. <b>Results:</b> The initial search resulted in 939 studies. After the full-text review, 44 studies were considered eligible. The pooled sensitivity and specificity of iPET for predicting end-of-treatment response were 0.78 (95% CI, 0.69-0.84) and 0.84 (95% CI, 0.78-0.88), respectively. On the basis of the pooled positive and negative LRs, iPET was not a reliable modality to exclude or confirm the end-of-treatment [¹⁸F]FDG PET results. The pooled PFS HR across all available datasets (<i>n</i> = 27) was 2.88 (95% CI, 2.35-3.52) for positive iPET (Deauville score [DS] 4-5). In datasets with HRs for positive iPET versus DS 5 alone, the pooled HRs were 2.36 (95% CI, 1.74-3.21) versus 5.59 (95% CI, 4.35-7.19). Furthermore, when datasets were limited to those with data on change in SUV_max versus DS 5 (<i>n</i> = 6), the pooled HRs were 3.41 (95% CI, 2.67-4.35) versus 5.59 (95% CI, 4.35-7.19), respectively. The pooled OS HR across all available datasets (<i>n</i> = 22) was 3.71 (95% CI, 2.93-4.69) for positive iPET. In datasets with HRs for positive iPET versus DS 5 alone (<i>n</i> = 5), the pooled HRs were 3.31 (95% CI, 2.09-5.24) versus 8.10 (95% CI, 6.04-10.85). Moreover, when datasets were limited to those with data on change in SUV_max versus DS 5 (<i>n</i> = 5), the pooled HRs were 4.54 (95% CI, 3.57-5.78) versus 8.10 (95% CI, 6.04-10.85). <b>Conclusion:</b> On the basis of our comprehensive systematic review and meta-analysis, DS 5 is a highly reliable predictor of unfavorable response to therapy on iPET. The utility of this threshold to escalate or modify therapy needs to be evaluated in future prospective trials.