In a comparison between metastatic Renal Cell Carcinoma and primary RCC, which shows more FDG uptake?

Metastatic Renal Cell Carcinoma (RCC) generally demonstrates higher uptake of 18F-fluorodeoxyglucose (FDG) compared to primary RCC. This increased uptake is attributed to the more aggressive nature and higher metabolic activity of metastatic tumors. When cancer cells metastasize, they often become more glycolytic, which is the mechanism behind FDG uptake since FDG is a radiotracer that mimics glucose.

In cases of primary RCC, the tumors may not always exhibit high levels of metabolic activity. Although some primary RCC lesions do show FDG uptake, the levels are typically lower than those observed in metastatic lesions. The metastatic sites, being more evolved and aggressive, utilize glucose more efficiently, leading to a greater uptake of FDG.

This difference in behavior emphasizes the importance of FDG PET in the staging and management of renal cell carcinoma. By identifying metastatic lesions that show increased FDG uptake, clinicians can better assess disease progression and tailor appropriate treatment strategies.