Prognostic value of tumor dissemination feature based on baseline 18F-FDG PET/CT in patients with newly diagnosed multiple myeloma.

We evaluated the prognostic value of the new 18F-fluorodeoxyglucose PET/computer tomography (18F-FDG PET/CT) parameter reflecting the spread of the tumor, the largest distance between two lesions (Dmax), and compared the predictive power of the new parameter with other parameters in newly diagnosed multiple myeloma (NDMM) patients. This retrospective study included 58 consecutive patients diagnosed with NDMM. 18F-FDG parameters [maximum standardized uptake value, metabolic tumor volume (MTV), and Dmax] and clinical data were analyzed for event-free survival (EFS). Univariate and multivariate analyses were performed using the Cox proportional hazards model, while survival outcomes were assessed via Kaplan-Meier curves. The median length of follow-up was 42 months (interquartile range, 18-62 months). Univariate analysis identified elevated serum calcium, elevated serum creatinine, MTV > 102.54 cm3, Dmax > 0.44 m, Dmax normalized by body height (Dmaxbh) > 0.27, Dmax normalized by body surface area (Dmaxbsa) > 0.24 m-1, and International Staging System stage as relevant prognostic factors for EFS (P < 0.1). Only Dmax > 0.44 m was found to be an independent prognostic factor for EFS on multivariate analysis (P = 0.047). The new PET parameter of Dmax, reflecting myeloma dissemination, has been shown the independent prognostic value in NDMM patients. This preliminary finding warrants further investigation.