e16564 Background: Positron emission tomography with (18F)-fluorodeoxyglucose (FDG-PET) is not considered a standard of care (SOC) in renal cell carcinoma (RCC) because of its variability in metabolic activity. We investigated the rate of PET-positivity in our institutional cohort and tested whether PET-positivity had prognostic value in metastatic (m)RCC. Methods: Patients with FDG-PET imaging at any time during the course of disease were identified from medical records. PET-positivity was defined according to PERCIST criteria and a five-point rating scale analogue to Deauville Scoring was used to stratify PET-avidity. Tracer uptake of the hottest lesion was measured as SUVmax. Clinical parameters and PET-positivitywere correlated with overall survival (OS). Kaplan-Meier plots, log-rank analyses, kendall rank correlation, univariate and multivariable cox regression models were employed, where appropriate. Results: A totalof 90 patients was analyzed. The median age was 64.0 (34.0-83.0) and 56 (62.2%) patients had clear cell RCC. Metastatic disease was present in 64 (71.1%) and 22 (24.4%) patients received ongoing medical treatment. 72 (80.0%) patients had prior nephrectomy. PET-positivity occurred in 57 (63.3%) patients, with similar rates among metastatic (41/64; 64%) and non-metastatic patients (16/26; 62%). PET-positive patients had shorter median OS compared to PET-negative patients (38.5 months (CI95:24.5-NR) vs. not reached (CI95: 69.6-NR), P= 0.0013). A weak correlation was found between PET-Uptake and histologic grade (Kendall’s tau 0.22; P= 0.03). Prior nephrectomy, presence of primary lesions, presence of distant metastases, histologic grade and PET-positivity were significant predictors of OS in univariate regression. In multivariable analysis, only PET-positivity remained significant (HR 4.1 (CI95: 1.1-15.4), P= 0.04). Conclusions: RCC is a metabolically active cancer, which in the majority of patients is suitable for FDG-PET diagnostic procedures. PET-positivity was an independent prognostic factor for OS in RCC, indicating its putative clinical use. Further studies to define the role of FDG-PET imaging in RCC are ongoing.
Better Late than Early: FDG-PET Imaging in Metastatic Renal Cell Carcinoma: Figure 1.