A Comparison of Skin Staining after Sentinel Lymph Node Biopsy in Women Undergoing Breast Cancer Surgery Using Blue Dye and Superparamagnetic Iron Oxide Nanoparticle (SPIO) Tracers

SIMPLE SUMMARY: Both superparamagnetic iron oxide nanoparticles (SPIO) and blue dye (BD) have been reported to cause skin staining after breast-conserving surgery. SPIO is a novel tracer that has been shown to identify sentinel lymph nodes (SLNs) in patients with breast cancer. Our study was the first to compare the incidence and size of skin staining between the two tracers. We reported on these outcomes in a preplanned secondary analysis of a prospective clinical trial in which women received both SPIO and BD. This study investigated whether there was a difference in the incidence and size of skin staining between SPIO and BD after SLN-dissection. In all, 270 women were operated on with breast-conserving surgery and received SPIO, and 204 of these women also received BD. After 24 months of follow up, there was no statistically significant difference between the two tracers with regard to the size and incidence of skin staining. ABSTRACT: Superparamagnetic iron oxide nanoparticles (SPIO) are a tracer for sentinel lymph node (SLN) detection. In a preplanned secondary analysis of a prospective clinical trial (SentiDose) we reported on skin staining after SPIO and blue dye (BD) injections. For SPIO, either a 1.5 mL retroareolar injection on the day of surgery or a 1.0 mL peritumoral/retroareolar injection 1–7 days before surgery was given. A 1.0 mL sub-/intradermal periareolar injection of BD was also administered to all these women. Staining was then assessed at 6, 12 and 24 months after surgery. A total of 270 women received SPIO and were operated on with breast-conserving surgery. Of these, 204 women also received BD. A total of 58 (21.5%) women had an SPIO stain 6 months postoperatively with a median size of 6.8 cm(2) (p = 0.56), while 51 (25.0%) had a BD stain with a median size of 8.5 cm(2) (p = 0.93). The incidence and size of SPIO and BD staining decreased over time reciprocally. At 24 months, the incidence and median size of SPIO was 23 (8.6%) and 4 cm(2), respectively. For BD, the incidence was 14 (6.3%, p = 0.13), and the median size was 3.5 cm(2) (p = 0.18). There was, therefore, no statistically significant difference in the incidence or size of skin staining between SPIO and BD over time.