Diagnostic brain-to-liver [¹⁸f]fdg uptake ratio predicts survival in multiple myeloma: A retrospective study

[¹⁸F]FDG PET/CT has been widely used in oncology for diagnosis and treatment monitoring. Reduced cerebral [¹⁸F]FDG uptake has been observed in patients with disseminated malignancies, potentially associated with the Warburg effect and elevated lactate levels. This study investigated the prognostic relevance of the brain-to-liver [¹⁸F]FDG uptake ratio (BLR) in MM patients who underwent PET/CT at diagnosis.

BLR was calculated as the ratio between the mean standardized uptake value (SUV) of the whole brain and that of the liver. A total of 72 patients were retrospectively included in the study (58% male; median age 65 years (IQR55;70); 67% were classified as ISS stage III).

BLR, as a continuous variable, showed a statistically significant difference between groups according to sex (p = 0.004), overweight status (p = 0.005), and ISS stage (p = 0.03), and was negatively correlated with β₂-microglobulin (r= - 0.42, p < 0.001). With a median follow-up of 23 months (IQR 8; 65), 74% patients had died from MM-related causes. Patients with BLR > 2.7 demonstrated superior 60-month overall survival (52%vs.10%, p = 0.002) and progression-free survival (19%vs.3%, p = 0.003), respectively. Multivariate Cox regression confirmed BLR (HR 1.86 95%CI: 1.03-3.33, p = 0.038 (OS); HR 1.93 95%CI: 1.13-3.29, p = 0.016 (PFS))as an independent factor and the use of autologous hematopoietic cell transplantation (HCT) as consolidation for both OS and PFS. In addition, ISS stage III was also a prognostic factor for OS.

Higher brain-to-liver [¹⁸F]FDG uptake ratio (> 2.7) at diagnosis predicts better clinical outcomes in multiple myeloma. BLR is significantly associated with established clinical markers of tumor burden in multiple myeloma. These findings suggest that BLR is a feasible and reproducible metric with potential prognostic value in multiple myeloma.