Use of gallium-68 prostate-specific membrane antigen positron-emission tomography for detecting lymph node metastases in primary and recurrent prostate cancer and location of recurrence after radical prostatectomy: an overview of the current literature

Objectives: To review the literature to determine the sensitivity and specificity of gallium-68 prostate-specific membrane antigen (68Ga-PSMA) positron-emission tomography (PET) for detecting pelvic lymph node metastases in patients with primary prostate cancer (PCa), and the positive predictive value in patients with biochemical recurrence (BCR) after initial curative treatment, and, in addition, to determine the detection rate and management impact of 68Ga-PSMA PET in patients with BCR after radical prostatectomy (RP). Materials and Methods: We performed a comprehensive literature search. Search terms used in MEDLINE, EMBASE and Science Direct were ‘(PSMA, 68Ga-PSMA, 68Gallium-PSMA, Ga-68-PSMA or prostate-specific membrane antigen)’ and ‘(histology, lymph node, staging, sensitivity, specificity, positive predictive value, recurrence, recurrent or detection)’. Relevant abstracts were reviewed and full-text articles obtained where possible. References to and from obtained articles were searched to identify further relevant articles. Results: Nine retrospective and two prospective studies described the sensitivity and specificity of 68Ga-PSMA PET for detecting pelvic lymph node metastases before initial treatment, which ranged from 33.3% to 100% and 80% to 100%, respectively. In eight retrospective studies, the positive predictive value of 68Ga-PSMA PET in patients with BCR before salvage lymph node dissection ranged from 70% to 100%. The detection rate of 68Ga-PSMA PET in patients with BCR after RP in the PSA subgroups