68 Ga-PSMA PET/CT based primary staging and histological correlation after extended pelvic lymph node dissection at radical prostatectomy

Prostate-specific membrane antigen positron emission tomography-computed tomography (PSMA PET/CT) represents the upcoming standard for the staging of prostate cancer (PCa). However, there is still an unmet need for the validation of PSMA PET/CT at primary staging and consecutive histological correlation. Consequently, we decided to analyze the prediction parameter of PSMA PET/CT at primary staging. We relied on 90 ≥ intermediate-risk PCa patients treated with radical prostatectomy (RP) and extended pelvic lymph node dissection. All patients were administered to 68Ga-PSMA PET/CT prior to surgery. 68Ga-PSMA PET/CT data were retrospectively reevaluated by a single radiologist and consequently compared to histological results from RP. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for the detection of lymph node metastases were analyzed per-patient (n = 90), per-pelvic side (n = 180), and per-anatomic-region (external iliac artery and vein left/right vs. obturator fossa left/right vs. internal iliac artery left/right) (n = 458), respectively. Sensitivity, specificity, PPV, and NPV per-patient were: 43.8, 96.0, 70.0, and 88.8%, respectively. Sensitivity, specificity, PPV, and NPV per-pelvic-side were: 42.9, 95.6, 56.3, and 92.7%, respectively. Sensitivity, specificity, PPV, and NPV per-anatomic-region were: 47.6, 98.9, 66.7, and 97.5%, respectively. Negative 68Ga-PSMA PET/CT results were highly reliable in our study. Positive 68Ga-PSMA PET/CT results, however, revealed less reliable results. Larger and ideally prospective trials are justified to clarify the potential role of PSMA PET/CT based primary staging.