Sentinel lymph node dissection in prostate cancer using superparamagnetic particles of iron oxide: early clinical experience

Superparamagnetic nanoparticles of iron oxide (SPION) were shown to be non-inferior to standard radioisotope tracer in breast cancer and may be used as an alternative to identify sentinel lymph nodes (SLN). The aim of this study was to assess the feasibility of sentinel lymph node dissection (SLND) using SPION in prostate cancer and to evaluate its diagnostic accuracy. Twenty patients with intermediate- and high-risk prostate cancer were prospectively enrolled in 2016. After intraprostatic injection of SPION, SLND using magnetometer was performed the following day. Extended pelvic lymph node dissection (ePLND) was added as a reference standard test. The diagnostic performance of the test were evaluated, as well as the rate of in vivo detected SLN. Surgical times of SLND and ePLND were compared using paired two-sample t test. In total, 97 SLN were detected with median 5 (IQR 3-7) per patient. Non-diagnostic rate of the procedure was 5%. In total, 19 nodal metastases were found in 5 patients, of which 12 were located in SLN. The sensitivity per patient for the whole cohort was 80% and per node 56%. If only patients with at least one detected SLN were considered, the sensitivity per patient and per node reached 100 and 82%, respectively. A median of 20 LNs (IQR 18-22) were removed by subsequent ePLND. Surgical times of SLND and ePLND differed significantly, with medians of 17 and 39 min, respectively (p < 0.001). SLND with SPION is feasible and safe in prostate cancer and the diagnostic accuracy is comparable to the published results of radioguided procedures. In open surgery, SPION may be used as an alternative tracer with its main advantage being the lack of radiation hazard.