Ga-67-PSMA IT for Radioguided Surgery of Lymph Node Metastases in Patients With Biochemical Recurrence of Prostate Cancer

摘要

PurposeRadioguided lymph node dissection in patients with prostate cancer, and suffering from biochemical recurrence has been described thoroughly during the past few years. Several prostate-specific membrane antigen (PSMA)-directed ligands labeled with In-111, Tc-99m, and Ga-68 have been published; however, limitations regarding availability, short half-life, high costs, and unfavorable high energy might restrict frequent use. This study aims at introducing Ga-67 as a promising radionuclide for radioguided surgery.MethodsRetrospective analysis was performed on 6 patients with 7 PSMA-positive lymph node metastases. Ga-67-PSMA IT (imaging and therapy) was synthesized in-house and intravenously applied according to 13 2b of the German Medicinal Products Act. Radioguided surgery was performed 24 hours after injection of Ga-67-PSMA IT using a gamma probe. Patient urine samples were collected. Occupational and waste dosimetry was performed to describe hazards arising from radiation.Results(67)Ga-PSMA application was tolerated without adverse effects. Five of 7 lymph nodes were detected on 22-hour SPECT/CT in 4 of 6 patients. During surgery, all 7 lymph node metastases were identified by positive gamma probe signal. Relevant accumulation of Ga-67 was observed in lymph node metastases (32.1 +/- 15.1 kBq). Histology analysis of near-field lymph node dissection revealed more lymph node metastases than PET/CT (and gamma probe measurements) identified. Waste produced during inpatient stay required decay time of up to 11 days before reaching exemption limits according to German regulations.ConclusionsRadioguided surgery using Ga-67-PSMA IT is a safe and feasible option for patients suffering from biochemical recurrence of prostate cancer. Ga-67-PSMA IT was successfully synthesized according to Good Manufacturing Practice guidelines. Radioguided surgery with Ga-67-PSMA IT does not lead to relevant radiation burden to urology surgeons and represents a novel interdisciplinary approach in nuclear medicine and urology.