Any Role of FDG PET in Renal Cancer?

[¹⁸F] Fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F] FDG-PET/CT) has traditionally been considered suboptimal for the evaluation of renal tumors due to intense physiological tracer accumulation in the urinary tract. However, incidental detection of renal masses can occur during [¹⁸F] FDG-PET examinations, and recognizing that FDG uptake varies according to tumor type can aid differential diagnosis. In patients with renal failure or those undergoing dialysis, reduced urinary excretion lowers background activity, paradoxically improving the visualization of renal tumors. Recent studies have demonstrated that high-grade and sarcomatoid renal cell carcinomas (RCCs) exhibit intense [¹⁸F] FDG uptake associated with poor prognosis, whereas benign and low-grade lesions show relatively low uptake. Although [¹⁸F] FDG-PET/CT has limited sensitivity for nodal staging, it provides high diagnostic accuracy for distant metastases, including osteolytic bone lesions. During postoperative surveillance and restaging, PET/CT contributes to early detection of recurrence and assists in therapeutic decision-making, particularly in high-risk or dialysis patients. In therapeutic monitoring, changes in metabolic parameters-such as SUV_max, metabolic tumor volume, and total lesion glycolysis-correlate with progression-free and overall survival during tyrosine kinase inhibitor or immune checkpoint inhibitor therapy. These parameters complement Response Evaluation Criteria in Solid Tumors (RECIST) and support metabolic response criteria such as PET Response Criteria in Solid Tumors (PERCIST). Moreover, novel tracers developed to overcome the intrinsic limitations of [¹⁸F] FDG, including [¹¹C] Acetate, [¹⁸F] Fluoromisonidazole, and prostate-specific membrane antigen ligands, have shown promise in differentiating fat-poor angiomyolipoma, evaluating tumor hypoxia, and detecting FDG-negative metastases. This review discusses the current role, limitations, and future perspectives of [¹⁸F] FDG-PET in the management of renal tumors, with particular focus on RCC.