68Ga-PSMA-PET/CT helps to select patients for salvage radical prostatectomy with local recurrence after primary radiotherapy for prostate cancer

Objective To investigate the diagnostic performance of gallium-68 prostate-specific membrane antigen positron emission tomography/computed tomography (Ga-68-PSMA PET/CT) in patients with recurrent prostate cancer with regard to the presence of lymph node metastases (LNM) and local recurrences after primary radiotherapy. Patients and methods We retrospectively reviewed 142 patients following salvage radical prostatectomy (sRP), 50 of which had a(68)Ga-PSMA PET/CT performed as a preoperative staging module. Predictive clinical parameters were analysed in a multivariate Cox regression analysis. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) and the accuracy of(68)Ga-PSMA PET/CT were analysed with regard to LNM and local recurrence. Results In all, 613 lymph nodes were resected in 40 patients and 23 lymph nodes had metastatic deposits in 14 patients. In all patients local recurrence could have been found with(68)Ga-PSMA PET/CT. Sensitivity, specificity, PPV and NPV and accuracy on a per lymph node basis were 34.78% (16.38-57.2%), 100% (99.38-100%), 100%, 97.52% (96.69-98.15%) and 97.55% (96.00-98.62%). For detecting local recurrence, the sensitivity and PPV were both 100% with an accuracy of 100% (92.89-100%). Conclusion Ga-68-PSMA PET/CT should be the standard imaging in biochemical recurrent prostate cancer. With this imaging module one detects first local recurrence and can detect locoregional and distant metastases more precisely than standard CT and bone scan.