18F-FDG-PET/CT Imaging as Survival Predictor in Patients with Metastatic Uveal Melanoma

ABSTRACT Aims To correlate metabolic activity by 18F-FDG-PET/CT with survival in uveal melanoma patients with liver metastases (LM). Methods We undertook a retrospective study of 34 patients with uveal melanoma and LM who underwent a 18F-FDG-PET/CT at the time of metastatic diagnosis. Metabolic activity of LM was measured by standardized uptake value (SUV) and by grouping in 18F-FDG-PET-negative (lower or same metabolic activity in LM than in normal liver parenchyma (NLP) comparing to 18F-FDG-PET-positive (higher metabolic activity in LM than in NLP). These measures were correlated with overall survival (OS). Results Patients were treated in 2 institutions between 2004-2010. There were 19 women and 15 men. Median age was 62 years (30-84). Median follow-up was 16.7 months. Treatment of primary tumor was: 15 enucleation (44.1%), 3 resection (8.8%) and 16 brachytherapy (47.1%). LM were diagnosed on screening protocol and histologically confirmed if possible (85.3%). Median major diameter of LM was 20 mm (9-130). Median maximum SUV of LM was 8.7 (2-25). 18F-FDG-PET/CT was negative for metabolic activity in 6 patients and positive in 28 patients. All 6 patients with negative 18F-FDG-PET/CT were histologically confirmed. Metastatic disease treatments were: chemotherapy (27 patients), liver surgery (9 patients), liver stereotactic radiotherapy (2 patients), liver radiofrequency ablation (1 patient). Median OS was 18.8 months (CI 95% 7.2-30.4). Median OS was significantly higher (p = 0.001) in patients with 18F-FDG-PET-negative (median not reached) than in patients with 18F-FDG-PET-positive (15.1 months, CI 95% 11.5-18.7). Assessed as a continuous variable, maximum SUV in the liver was correlated with OS (p = 0.002, HR 1.1, CI 95% 1.03-1.2). Maximum SUV greater than 5 was related with poor prognosis (p = 0.025). Major diameter of LM in 18F-FDG-PET/CT was significantly correlated with OS (p  Conclusion Metabolically 18F-FDG-PET-negative liver metastases correlated with better OS in patients with metastatic uveal melanoma. Disclosure All authors have declared no conflicts of interest.