The relevance of nomograms for prediction of pelvic lymph node metastases in the prostate-specific membrane antigen (PSMA)-PET/CT era.

Abstract

Background/aims: Current guidelines suggest that the indications for pelvic lymph node (LN) dissection (PLND) during radical prostatectomy (RP) should rely on nomograms predicting their involvement. Positron emission tomography/computed tomography (PET/CT) with prostate-specific membrane antigen (PSMA) radioligand is gaining acceptance as routine diagnostic test before RP in patients with intermediate/high-risk prostate cancer (PC). In this study, we examined the effect of preoperative PET/CT on the accuracy of the nomograms.

Materials and methods: Patients with intermediate/high risk PC showing no extraprostatic disease on PET/CT-PSMA underwent RP with PLND and were followed postoperatively for at least 6 months. Patients with detectable (>0.1 ng/mL) postoperative prostate-specific antigen levels underwent re-evaluation with PET/CT-PSMA.

Results: A total of 70 patients underwent RP for intermediate (34 patients) or high-risk disease (36 patients). According to the Partin, MSKCC, and Briganti 2012 nomograms, positive LNs were expected in 7, 13, and 12 patients, respectively. At PLND, 1 positive LN was found in a single patient (p < 0.05 compared with the expected number of patients from all nomograms). Postoperatively, 10 patients developed detectable prostate-specific antigen levels. One patient exhibited radioligand uptake that could indicate LN involvement. Considering these 2 patients as failures, the negative predictive value of PSMA-PET/CT for LN involvement was 97.1%.

Conclusions: Preoperative PSMA-PET/CT with no extraprostatic uptake before RP in patients with intermediate to high-grade PC is highly accurate for ruling out LN involvement, superior to the routinely used nomograms. Its use induced stage migration, rendering predictive nomograms irrelevant.