To determine the diagnostic capabilities of combined prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) and sentinel node (SN) biopsy in PSMA PET/CT negative patients for the primary lymph node (LN) staging in prostate cancer (PCa) patients. Methods Between January 2017 and March 2019, retrospectively, all consecutive patients with primary diagnosed intermediate- or high-risk PCa who underwent a preoperative PSMA PET/CT (68Ga or 18F-DCFPyL) followed by robot-assisted radical prostatectomy and extended pelvic lymph node dissection (ePLND) were included. All patients without suspected LN metastases on PSMA PET/CT were considered candidates for SN biopsy with indocyanine green (ICG) -99mTc-nanocolloid or 99mTc-nanocolloid with free ICG as used tracers. The ePLND was used as reference standard. Results Of 53 patients, 22 had a positive PSMA PET/CT and 31 received subsequent SN biopsy after negative PSMA PET/CT. In total, 23 patients (43%) were pN1, of which 6 (26%) with a negative PSMA PET/CT and subsequent SN biopsy. The combined use of SN biopsy and PSMA PET/CT identified all pN1 patients (100% sensitivity, 95% Confidence Interval [CI] 86-100) and performed correct nodal staging in 50 of 53 patients (94% diagnostic accuracy, 95% CI 84-99). SN biopsy identified significantly smaller LN metastases (median diameter of 2.0 mm interquartile range [IQR] 1.0-3.8) than PSMA PET/CT (5.5 mm IQR 2.6-9.3; P = 0.007). Conclusion Combining both modalities led to a 94% accuracy for nodal staging in primary diagnosed intermediate- and high-risk PCa. Adding SN biopsy in patients with a negative PSMA PET/CT increases the combined sensitivity to 100% for detecting nodal metastases at ePLND. This diagnostic accuracy may provide valuable information for directing further treatment in PCa patients, such as PSMA PET/CT and SN biopsy rather than ePLND as preferred diagnostic approach for staging purposes of men prior to radiotherapy for PCa.

Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2019 Sep 27 [Epub ahead of print]

Florentien J Hinsenveld, Esther M K Wit, Pim J van Leeuwen, Oscar R Brouwer, Maarten L Donswijk, Corinne N Tillier, Erik Vegt, Henricus A M van Muilekom, Matthijs N van Oosterom, Fijs W B van Leeuwen, Henk G van der Poel

the Netherlands Cancer Institute, Netherlands., the Netherlands Cancer Institute, Leiden University Medical Center, Netherlands., Leiden University Medical Center, Netherlands.