Superparamagnetic iron oxide (SPIO) for sentinel lymph node detection in vulvar cancer

Sentinel lymph node (SLN) detection with superparamagnetic iron oxide (SPIO) nanoparticles has been widely studied and standardized for breast and prostate cancer, but there is scarce evidence concerning its use in vulvar cancer. The objective of this study was to compare SLN detection using a SPIO tracer injected at the time of the surgery detected by a magnetometer, with the standard procedure of using a technetium 99 radioisotope (Tc99) detected by a gamma probe, in patients with vulvar cancer.

The SPIO vulvar cancer study was a single-center prospective interventional non-inferiority study of SPIO compared to Tc99, conducted between 2016 and 2021 in patients who met the GROINSS-V study inclusion criteria for selective sentinel lymph node dissection in vulvar cancer.

We included 18 patients and a total of 41 SLNs. The level of agreement between tracers was 92.7% (80.6%-97.4%), corresponding to 38 out of 41 SLNs, which confirms the non-inferiority of SPIO compared to Tc99. The SLN detection rate per groin was 96.3 (81.7%-99.3) using Tc99 and 100% (87.5%-100%) using SPIO. Both tracers had a detection rate of 100% for positive lymph nodes.

The use of SPIO as a tracer for detecting SLNs in patients with vulvar cancer has shown to be non-inferior to that of the standard radiotracer, with the advantages of not requiring nuclear medicine and being able to inject it at the time of surgery after induction of anesthesia.