Renal cell carcinoma: clinical and prognostic value of 18F-FDG-PET/CT after surgery

1432 Objectives Several studies, often with divergent results, have discussed the perfomance of 18F-FDG-PET/CT (FDG-PET) at restaging for patients with renal cell carcinoma (RCC) but the possible prognostic role remain still undefined. The aim of this retrospective study was to evaluate the impact of restaging PET results on the survival of patients underwent to surgery for RCC, analysing the accuracy and potential prognostic value. Methods We reviewed 58 FDG-PET scans in 39 patients after surgery for RCC. Diagnostic accuracy of visually interpreted FDG-PET was evaluated based on final diagnoses obtained by histology (19/39 patients, pts), other imaging (enhanced CT 39/39 pts; Bone scan 20/39 pts; MRI 10/39 pts) and by follow-up (39/39 pts; median 31 months;). Additional information such as, influence on treatment decisions, and impact of FDG-PET findings on survival were assessed. Progression-free survival (PFS), overall survival (OS) using Kaplan-Meier method, and relative risk of progression (RRP) with Cox regression analysis were calculated. Results Suspicious recurrence of RCC was histologically (n = 16) or by diagnostic imaging and follow-up (n = 18) confirmed in 34/58 FDG-PET scans. Overall, the sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy using FDG-PET were 78%, 88%, 95%, 62%, 81% respectively. FDG-PET findings influenced therapeutic management in 18 cases (31%). Cumulative survival rates over 5 years in the PET-positive vs. the PET-negative group were 28% vs. 61%, respectively (p = 0.03). Cox regression analysis showed an high RRP for PET-positive compared to PET-negative patients (HR: 3.55; Chi-sq: 7.6; p=0,006). Conversely PET negative presents a lower RRP (HR: 0.4; Chi-sq: 1,4; p=0,02). Conclusions FDG-PET demonstrated to be a valuable tool in the treatment decision making and to predict survival and risk of progression of patients affected by renal cancer, despite a possible false negativity in some subtypes.