A dual-tracer approach for enhanced nodal staging in prostate cancer: the role of [¹⁸F]FDG PET/CT for detecting [⁶⁸ Ga]Ga-PSMA-11-negative metastases.

Abstract

A subset of newly diagnosed prostate cancer patients harbor occult lymph node metastases (LNM) that are not detected by standard [⁶⁸ Ga]Ga-PSMA-11 PET/CT, leading to potential understaging and suboptimal treatment planning. This study investigates the performance of [¹⁸F]FDG PET/CT as a secondary imaging tool to identify these PSMA-negative LNM. We retrospectively analyzed 133 patients with newly diagnosed prostate cancer who were considered node-negative (miN0) by [⁶⁸ Ga]Ga-PSMA-11 PET. All patients underwent a subsequent [¹⁸F]FDG PET/CT scan followed by radical prostatectomy and extended pelvic lymph node dissection (ePLND), with histopathology serving as the reference standard. The diagnostic efficacy of [¹⁸F]FDG PET/CT was benchmarked against the Briganti 2019 nomogram. Post-surgical pathology confirmed occult LNM in 11.3% (15/133) of patients. On a patient-based analysis, [¹⁸F]FDG PET/CT demonstrated a sensitivity of 73.3% and a specificity of 94.9% for detecting these occult LNM. This performance was significantly superior to the Briganti 2019 nomogram, with an area under the curve of 0.841 versus 0.621 (P < 0.001). Notably, multivariate analysis revealed that a lower serum prostate-specific antigen (PSA) level was an independent predictor of [¹⁸F]FDG-positive LNM (P = 0.013). In patients with newly diagnosed prostate cancer deemed node-negative by [⁶⁸ Ga]Ga-PSMA-11 PET, supplementary [¹⁸F]FDG PET/CT can identify a significant proportion of occult LNM missed by initial staging. Our findings suggest that this dual-tracer approach may be particularly beneficial for patients with lower serum PSA levels, potentially improving risk stratification and selection for ePLND.