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Ga-PSMA PET/CT scanning has been shown to be more sensitive than conventional imaging techniques in patients with prostate cancer. This prospective Australian multicenter study assessed whether Ga-PSMA PET/CT imaging affects management intent in patients with primary or recurrent prostate cancer. Before undertaking Ga-PSMA PET imaging, referring medical specialists completed a questionnaire detailing relevant demographic and clinical data as well as their proposed management plan. A separate follow-up questionnaire was completed after theGa-PSMA PET/CT scan results were available to determine whether the management plan would change. A total of 431 patients with prostate cancer from 4 Australian centers had pre- and post-Ga-PSMA management plans completed. Scans were obtained for primary staging of intermediate- and high-risk disease in 25% of patients and for restaging/biochemical recurrence in 75% of patients. Overall, Ga-PSMA PET/CT scanning led to a change in planned management in 51% of patients. The impact was greater in the group of patients with biochemical failure after definitive surgery or radiation treatment (62% change in management intent) than in patients undergoing primary staging (21% change). Imaging withGa-PSMA PET/CT revealed unsuspected disease in the prostate bed in 27% of patients, locoregional lymph nodes in 39%, and distant metastatic disease in 16%. Ga-PSMA PET/CT scans detect previously unsuspected disease and may influence planned clinical management in a high proportion of patients with prostate cancer. The impact was greater in patients with biochemical recurrence. These results demonstrate the potential clinical value ofGa-PSMA PET/CT in management of prostate cancer.

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See an invited perspective on this article on page 1969.68 Ga-PSMA (prostate-specific membrane antigen) PET/CT is increasingly used in men with prostate-specific antigen (PSA) failure after radical prostatectomy (RP) to triage those who will benefit from salvage radiation treatment (SRT). This study examines the value of PSMA-informed SRT in improving treatment outcomes in the context of biochemical failure after RP. Methods: We analyzed men with rising PSA after RP with PSA readings between 0.05 and 1.0 ng/mL, considered eligible for SRT at the time of PSMA. For each patient, clinical and pathologic features as well as scan results, including site of PSMA-positive disease, number of lesions, and a certainty score, were documented. Subsequent management, including SRT, and most recent PSA were recorded using medical records. Treatment response was defined as both PSA # 0.1 ng/mL and .50% reduction in PSA. Multivariate logistic regression analysis was performed for association of clinical variables and treatment response to SRT. Results: One hundred sixty-four men were included. PSMA was positive in 62% (n 5 102/164): 38 of 102 in the prostatic fossa, 41 of 102 in pelvic nodes, and 23 of 102 distantly. Twenty-four patients received androgen-deprivation therapy (ADT) and were excluded for outcomes analysis. In total, 99 of 146 received SRT with a median follow-up after radiation treatment of 10.5 mo (interquartile range, 6-14 mo). Overall treatment response after SRT was 72% (n 5 71/99). Forty-five percent (n 5 27/60) of patients with a negative PSMA underwent SRT whereas 55% (33/60) did not. In men with a negative PSMA who received SRT, 85% (n 5 23/27) demonstrated a treatment response, compared with a further PSA increase in 65% (22/34) in those not treated. In 36 of 99 patients with disease confined to the prostate fossa on PSMA, 81% (n 5 29/36) responded to SRT. In total, 26 of 99 men had nodal disease on PSMA, of whom 61% (n 5 16/26) had treatment response after SRT. On multivariate logistic regression analysis, PSMA and serum PSA significantly correlated with treatment response, whereas pT stage, Gleason score, and surgical margin status did not. Conclusion: PSMA PET is independently predictive of treatment response to SRT and stratifies men into a high treatment response to SRT (negative or fossa-confined PSMA) versus men with poor response to SRT (nodes or distant-disease PSMA). In particular, a negative PSMA PET result predicts a high response to salvage fossa radiotherapy.Key Words: prostate specific membrane antigen; PSMA; PET/CT; treatment outcome; biochemical failure; post radical prostatectomy J Nucl Med 2017; 58:1972 58: -1976 58: DOI: 10.2967 Radi cal prostatectomy (RP) is the most widely used treatment for men with localized prostate cancer (PC). After surgery, patients are monitored with serial prostate-specific antigen (PSA) measurements. Approximately 20%-50% of pT2-3, node-negative PC patients treated with RP will experience biochemical recurrence, particularly those with poorly differentiat...