Preoperative PSMA-PET/CT as a predictor of biochemical persistence and early recurrence following radical prostatectomy with lymph node dissection

Background: This study aims to evaluate the predictive value of lymph nodes (LN) suspicious for metastases on preoperative prostate-specific membrane antigen (PSMA) PET/CT for biochemical persistence (BCP) and early biochemical recurrence (BCR) following robotic-assisted radical prostatectomy (RARP) with extended pelvic LN dissection (ePLND).

Methods: We evaluated 213 patients with intermediate and high-risk prostate cancer (PCa) who underwent clinical staging with preoperative ⁶⁸Ga- or ¹⁸F-PSMA-PET/CT scan and subsequent RARP with ePLND. Patients were grouped as PSMA- or PSMA+ depending on their LN status on PSMA-PET/CT and subdivided according to histological LN status in pN0 or pN1. Diagnostic accuracy of PSMA-PET/CT for the detection of pN1 was evaluated. BCP was defined as a first postoperative serum PSA level ≥0.1 ng/mL 6-12 weeks following RP. Early BCR was defined as detectable PSA > 0.2 ng/mL within 12 months of follow-up. Univariable logistic regression analyses were used to evaluate the effect of PSMA+ on BCP and BCR.

Results: Forty patients (19%) were PSMA+. The overall incidence of pN1 was 23%. Sensitivity, specificity, PPV and NPV on a per patient level for the detection of pN1 was 29%, 84%, 35%, and 80% respectively. BCP was observed in 26 of 211 patients (12%) and early BCR in 23 of 110 patients (21%). The presence of PSMA+ was a significant predictor for BCP (OR 7.1, 2.9-17.1 95% CI) and BCR (OR 8.1, 2.9-22.6 95% CI).

Conclusion: Preoperative PSMA-PET/CT may be a valuable tool for patient counseling for RARP and ePLND as it is a significant predictor for the risk of postoperative BCP and early BCR. We conclude that an ePLND should not be avoided in men with intermediate or high-risk PCa and preoperative negative PSMA-PET/CT, as 20% have microscopic LN metastasis.