(UroToday.com) It is now well established that PSMA PET/CT is more sensitive than conventional imaging. As such, PET/CT scan might lead to the identification of nodal metastases (e.g., cN1) in prostate cancer (PCa) patients considered for radical prostatectomy (RP). However, there are no data addressing the performance characteristics and prognostic value of a positive PET/CT in the nodes for the identification of men more likely to recur.
Despite the growing evidence on the accuracy of prostate-specific-membrane-antigen (PSMA) PET/CT, evidence on its clinical relevance as a primary staging tool is lacking. This study aims to evaluate the predictive value of suspected lymph nodes (LN) metastases on PSMA PET/CT for biochemical persistence (BCP) and early biochemical recurrence (BCR) following radical prostatectomy (RP) with extended pelvic lymph node dissection (ePLND).
All patients who underwent RP between September 1st, 2016, and October 1st, 2020 were evaluated. Men with newly diagnosed intermediate or high-risk PCa who underwent a preoperative 68Ga/18F-PSMA PET/CT and subsequent ePLND were included. Performance of PSMA PET/CT was determined on a per-patient level. BCP was defined as a first post-operative serum PSA level ≥ 0.1 ng/mL between 6-20 weeks following RP. Early BCR was defined as detectable PSA > 0.2 ng/mL ≤ 12 months of follow-up. Patients were grouped as PSMA- or PSMA+ depending on their LN status on PSMA PET/CT and subdivided according to histological LN status (pN) as determined by ePLND.
From 1058 consecutive RP patients, 213 met the inclusion criteria – which naturally includes some selection bias for men who received the pre-operative staging studies.
There were no statistically significant differences between PSMA- and PSMA+ groups regarding age, preoperative PSA level, T-stage, ISUP grade, surgical margins, or LN metastases. Median number of resected LN was 20 (IQR 15-26).
Results of PSMA PET/CT versus histological results of ePLND are presented in Table 1. Sensitivity, specificity, PPV, NPV and accuracy for preoperative detection of metastatic LNs were 29%, 83%, 33%, 80% and 71% respectively.
pN1 (%)pN0 (%)Total (%)
PSMA+14 (33%)28 (67%)42 (100%)
PSMA-34 (20%)137 (80%)171 (100%)
Total48 165 213
BCP was observed in 26 of 211 patients (12%) and early BCR in 23 of 110 patients (21%). The incidence of BCP and BCR for patients subdivided according to their PSMA and pN status is illustrated in Figure 1.
No correction was made for other risk factors. Patients with PSMA+/pN1 had a significantly increased risk of BCP and BCR compared with PSMA-/pN1 (p=0.004; p<0.001).
These results are in line with other studies being presented today. The authors conclude that an ePLND should not be avoided in men with a pre-operative negative PSMA PET/CT, as 20% of patients do have histological N1 disease. Men with positive pre-operative PSMA PET/CT and confirmed pN1 disease have a significantly increased risk of BCP and early BCR compared to those with negative PSMA PET/CT, and should potentially be considered for adjuvant therapy.Presented by: D.J.H. Baas, Utrecht, Netherlands
Written by: Thenappan (Thenu) Chandrasekar, MD – Urologic Oncologist, Assistant Professor of Urology, Sidney Kimmel Cancer Center, Thomas Jefferson University, @tchandra_uromd on Twitter during the 2021 European Association of Urology, EAU 2021- Virtual Meeting, July 8-12, 2021.