Diagnostic and prognostic role of F-FDG PET/CT for sarcomatoid differentiation in renal cell carcinoma.

BACKGROUND

Sarcomatoid differentiation is an invasive dedifferentiated feature of tumor and associated with poor prognosis in renal cell carcinoma (RCC) patients. This study aimed to evaluate the utility of F-FDG PET/CT in predicting sarcomatoid differentiation in RCC and its potential prognostic value.

RESULTS

This retrospective study assessed newly diagnosed sarcomatoid differentiation renal cell carcinoma (SDRCC) patients who were staged using F-FDG PET/CT. Patients were categorized into high-grade sarcomatoid differentiation RCC (HG-SDRCC), low-grade sarcomatoid differentiation RCC (LG-SDRCC), and non-sarcomatoid differentiation RCC (non-SDRCC). The maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were compared. Overall survival (OS) and disease-free survival (DFS) were analyzed. SUVmax, MTV, TLG, and SUVmean values were significantly higher in SDRCC compared to non-SDRCC (P < 0.05). Additionally, SUVmax, TLG, and SUVmean were significantly higher in HG-SDRCC compared to non-HG-SDRCC (P < 0.05). ROC curves revealed that SUVmax and SUVmean were effective for distinguishing HG-SDRCC from non-HG-SDRCC. The log-rank test identified SUVmax > 11, MTV > 95, TLG > 500, SUVmean > 5.2, invasion of peripheral tissue and/or organs, and metastasis as risk factors for SDRCC patients. Multivariate Cox proportional hazards model analyses indicated that TLG > 500 was a risk factor for poor DFS, while SUVmax > 11 and SUVmean > 5.2 were risk factors for poor OS.

CONCLUSIONS

F-FDG PET/CT can effectively differentiate HG-SDRCC with more aggressive malignancy. The prognostic model developed in this study demonstrates that metabolic parameters, particularly TLG for DFS and SUVmax/SUVmean for OS, serve as more robust predictors of patient outcomes than the degree of sarcomatoid differentiation.