Diagnostic and prognostic utility of PSMA-PET/CT in node-metastatic prostate cancer

To measure the sensitivity of prostate-specific membrane antigen-positron emission tomography/computed tomography (PSMA-PET/CT) for detecting lymph node involvement (LNI) in patients undergoing radical prostatectomy (RP) and extended pelvic lymph node dissection (PLND) and to evaluate whether PSMA nodal status independently predicts oncological outcomes.

We identified patients with localised or locoregional prostate cancer who underwent PSMA-PET/CT followed by RP (2021-2024) at a high-volume centre and had pathologically confirmed LNI (pN1) on PLND. We evaluated the sensitivity of PSMA-PET/CT for detecting pN1 disease. Associations between PSMA-PET/CT and biochemical recurrence (BCR), any radiographic recurrence, and distant recurrence were evaluated using Cox regression models.

Overall, PSMA-PET/CT detected LNI in 24 of 79 patients with pN1 disease, a sensitivity of 30% (95% confidence interval [CI] 21-42%). PSMA-positive nodal disease (clinical N1 [cN1]) was significantly associated with BCR (hazard ratio [HR] 2.34, 95% CI 1.26-4.36; P = 0.009), radiographic recurrence (HR 4.23, 95% CI 1.86-9.58; P < 0.001), and distant radiographic recurrence (HR 5.81, 95% CI 1.79-18.8; P = 0.002). The 1-year risk of BCR approached 90% for those with cN1 disease. Median metastatic focus size was larger in cN1 vs cN0 patients (1.1 vs 0.3 cm; P < 0.001). Limitations include relatively short follow-up.

Due to low sensitivity, PSMA-PET/CT without evidence of nodal disease does not obviate the need for PLND. However, PSMA-avid nodal disease portends a nearly inevitable short interval recurrence and radiographic progression, supporting treatment intensification.