Eirini Pantiora: Magnetic Techniques in Breast Cancer Surgery

Abstract

Preoperative tumor localization and axillary mapping in breast cancer surgery are integral for successful breast conserving surgery and axillary staging. They can be performed with a variety of markers and tracers, including magnetic seeds and a liquid sentinel node tracer containing superparamagnetic iron oxide (SPIO) nanoparticles. Although numerous studies have demonstrated the safety and efficacy of both magnetic seeds and SPIO in breast cancer surgery, further research is needed to optimize their application and maximize their potential benefits.

Paper I presents a systematic review and meta-analysis of studies that have investigated the role of SPIO for sentinel lymph node biopsy (SLNB). The findings confirm that SPIO performs comparably to radioisotope while highlighting knowledge gaps regarding the optimal dose, timing, and site of SPIO injection to minimize side-effects and facilitate tailoring of treatment.

Paper II reports a pragmatic, multicenter randomized clinical trial comparing the use of magnetic seed and SPIO to conventional guidewire and SPIO in non-palpable breast tumors. In 426 patients, both methods demonstrated equivalent re-excision rate, SLN detection, and resection ratio. However, the combination of magnetic seed and SPIO resulted in shorter operative times, fewer failed localizations and improved surgical logistics.

Paper III presents the results of a prospective cohort study that investigated the feasibility and efficacy of SPIO for SLNB in patients undergoing primary systemic therapy (PST) for breast cancer. The results showed that SPIO performed comparably to radioisotope (RI) but detected more sentinel lymph nodes and demonstrated a higher detection rate of metastatic sentinel lymph nodes. The findings suggest that SPIO injection before PST is both feasible and beneficial for enhancing axillary mapping in this patient population, though further studies are needed to refine the optimal timing of administration.

Paper IV consists of a health economic analysis of the trial from Paper II. It explores the financial implications of the implementation of a magnetic marker compared to the guidewire. Through a cost-minimization approach that considered all direct and indirect costs, the study demonstrated that although the magnetic marker is more expensive as a device, incorporating it in the Swedish healthcare system is more cost-effective than the guidewire.