Relationship between spleen volume, spleen/liver SUVmax ratio, and percentage change and overall survival in patients undergoing immunotherapy

Aims: This study aimed to investigate the pre- and post-treatment associations between spleen volume (SV), spleen/liver maximum standardized uptake value (SUVmax) ratio (SLR), and percent change (Δ) and overall survival (OS) in patients undergoing immunotherapy. Methods: This retrospective study included 89 patients who underwent 18F FDG PET/CT imaging before immunotherapy (baseline) and during post-treatment at 3 and 6 months. SV, spleen SUVmax, and liver SUVmax parameters were determined based on PET/CT images. Patients’ ages and date of mortality were recorded. Results: In the present study, 52 (58.4%) were men, and the median OS was 17.7 (4-83) months. Furthermore, 63 out of 89 patients (70.8%) died during the study period. Baseline median SV value was 230 ml (47-1870). Baseline median SLR value was 0.80 (0.33-1.48). Median ΔSV1 at baseline and at 3 months post-treatment was -1.34 (-55.03-155.37). Percent change in SLR baseline and post-treatment (ΔSLR1) median was -0.52 (-48.39-121.02). Moreover, SLR1 had a sensitivity of 64.2% and specificity of 65.2% in detecting mortality with a cutoff value of >0.80. For a SLR1 value of ≤0.79, median OS was 29.5 months and 1-3-year survival was 87/37%. SLR1 and SLR3 were independent prognostic factors for OS (p=0.003 and p=0.004, respectively). Conclusion: SV values before and at 3 months post-immunotherapy and SLR values before and at 6 months post-treatment were prognostic factors for OS. Higher SLR1 and SLR3 values from 18F FDG PET/CT before and at 6 months post-treatment were independent prognostic factors and associated with shorter OS.