Prostate-specific membrane antigen-guided salvage lymph node dissection in recurrent prostate cancer: a novel technology to detect lymph node metastases

PURPOSE OF REVIEW: With Gallium (Ga)-prostate-specific membrane antigen (PSMA) PET/computed tomography (CT) as emerging imaging technique offering superior detection rates in biochemical recurrent prostate cancer, salvage lymph node dissection has gained increasing interest in localized oligometastatic prostate cancer. Currently, PSMA-targeting small molecules cannot only be linked to positron-emitting isotopes for imaging but also be labelled with gamma-radiation emitting isotopes. These modified PSMA agents are evaluated for intraoperative guidance for resection of metastatic lymph nodes. This review aims to review current knowledge on the novel technique of PSMA-radioguided surgery. RECENT FINDINGS: Recently radiolabeling of PSMA ligands with Indium and Technetium as gamma emitter has been established. After preoperative intravenous injection of these novel PSMA agents single photon emission computed tomography/CT imaging can be performed using the gamma-emitting properties. Although its diagnostic performance seems to be inferior to Ga-PSMA PET/CT, intraoperative guidance by the use of a gamma probe was reported to facilitate detection and resection of tumour-infiltrated soft tissue. First follow-up data suggests favourable outcomes concerning prostate-specific antigen progression and treatment-free survival in a subset of patients. SUMMARY: Although current knowledge is still limited and published data is sparse salvage surgery in recurrent prostate cancer facilitated by gamma-emitting PSMA agents seems feasible. However, careful identification of ideal candidates for those procedures is mandatory.