Magnetic sentinel node and occult lesion localization in breast cancer (MagSNOLL Trial)

Abstract

Background: Non-palpable breast cancers require localization-guided surgery and axillary staging using sentinel lymph node biopsy (SLNB). This study investigated the novel technique of magnetic-guided lesion localization and concurrent SLNB, which avoids the need for wire-guided localization and radioisotopes.Methods: An ultrasound-guided intratumoral injection of magnetic tracer (0⋅5 ml) was performed in a protocol-driven predefined minimum of ten patients with palpable breast cancer to assess the ability of the magnetic tracer safely to localize the tumour at the site of injection and concurrently drain to the lymphatics. Once successful lesion localization had been confirmed (peak magnetometer count retained at the centre of the tumour), the technique was undertaken in a further 20 patients with non-palpable breast cancers awaiting wide local excision and SLNB. All patients underwent SLNB with both the magnetic and standard dual (radioisotope and Patent Blue V dye) techniques.Results: Thirty-two patients were recruited, of whom 12 (1 with bilateral disease) presented with palpable and 20 with non-palpable breast cancer. Peak magnetometer counts were retained at the tumour centre in all palpable (13) and non-palpable (20) breast cancers. Re-excisions for involved margins were necessary in two patients with non-palpable breast cancers. The sentinel lymph node identification rates were 28 of 33 procedures for the magnetic technique alone, 32 of 33 for the magnetic technique combined with blue dye, and 32 of 33 for the standard dual technique.Conclusion: Magnetic lesion localization is feasible, with intratumoral magnetic tracer injection combined with a periareolar injection of blue dye for subsequent SNLB. * Other members of the MagSNOLL Trialists Group are co-authors of this study and can be found under the heading Collaborators

Surgical treatment of nonpalpable primary invasive and in situ breast cancer

“…Consequently, patients with in situ disease were excluded from the trial. 62 Results from the first 20 patients with nonpalpable breast cancer demonstrated successful radiological and intraoperative localization in all patients, with re-excisions (second operations) performed for involved margins in two patients. 62 The mean volume of excised specimens was 49.5 cm 3 (standard deviation [SD] 30.6) and the calculated resection ratio (CRR) was 2.5 (SD 2.2).…”

“…62 Results from the first 20 patients with nonpalpable breast cancer demonstrated successful radiological and intraoperative localization in all patients, with re-excisions (second operations) performed for involved margins in two patients. 62 The mean volume of excised specimens was 49.5 cm 3 (standard deviation [SD] 30.6) and the calculated resection ratio (CRR) was 2.5 (SD 2.2). 62 This study confirms the proof of principle of the magnetic technique for lesion localization and lends support to further analysis within an extended cohort.…”

“…62 The mean volume of excised specimens was 49.5 cm 3 (standard deviation [SD] 30.6) and the calculated resection ratio (CRR) was 2.5 (SD 2.2). 62 This study confirms the proof of principle of the magnetic technique for lesion localization and lends support to further analysis within an extended cohort.…”

How Can Nanoparticles be used in Sentinel Node Detection?

“…This area requires prospective evaluation to confirm these findings but it is essential that on-going research attempts to reduce iron retention at injection sites. The injection of lower volumes (0.5 ml) intratumorally was explored clinically but resulted in low sentinel node identification rates compared with the standard combined technique (85 vs 97%) [17]. Porcine models demonstrated a significant inverse relationship between increasing injection volumes and percentage iron uptake (relative to injected dose) by sentinel nodes (p < 0.001) [15].…”

Sentinel lymph node assessment in breast cancer patients receiving neo‐adjuvant chemotherapy: to biopsy before or after?

“…magnetised clips with permanent ultrasound enhancement that do not substantially interfere with MRI) should be able to assist in our quest to improve the accuracy of post‐NAC sentinel node biopsy and further research in this field is urgently needed. Somewhat speculative at this stage but capitalising on encouraging results of SentiMAG and MagSNOLL trials, use of a hand‐held magnetometer device and superparamagnetic iron oxide nanoparticle tracer could also be explored if the tracer remains retained in nodes for the duration of NAC; or using a magnetised clip as an alternative (figure). Subsequent simultaneous use of blue dye/radiocolloid‐gamma probe and a hand‐held magnetometer where sentinel node has been magnetically marked before NAC may help minimise the impact of changes in lymphatic drainage patterns following NAC.…”