The superparamagnetic iron oxide is equivalent to the Tc99 radiotracer method for identifying the sentinel lymph node in breast cancer

Impact of low dose superparamagnetic iron oxide tracer for sentinel node biopsy in breast conserving treatment on susceptibility artefacts on magnetic resonance imaging and contrast enhanced mammography

BACKGROUND

Residual particles of superparamagnetic iron oxide (SPIO) tracer, used for sentinel node biopsy, cause susceptibility artefacts on breast Magnetic Resonance Imaging (MRI). We investigated the impact of these artefacts on the imaging quality of MRI and explored whether contrast-enhanced mammography (CEM) could be an alternative in the follow-up of breast cancer patients.

MATERIALS AND METHODS

Data on patients' characteristics, injection site, presence, size (mm) of artefacts on full-field digital mammography (FFDM)/CEM, MRI after 1 ml SPIO was recorded. Image quality scored by two breast radiologists using a 4-point Likert system: 0: no artefacts 1: good diagnostic quality 2: impaired but still readable 3: hampered clinical assessment. Continuous variables reported as means and standard deviations (SD), categorical variables as count and percentage.

RESULTS

On FFDM/CEM, performed 13 months postoperatively, no iron SPIO particles were detected, with a Likert score of 0. In all MRI (100%) images, executed at 16.6 months after SPIO injection, susceptibility artefacts at the injection sites i.e., retroareolair and lateral quadrant were observed with a mean size of 41.9 ± 9.8 mm (SD) by observer 1, and 44.8 ± 12.5 mm (SD) by observer 2, independent of the injection site. Both observers scored a Likert score of 2: locally impaired on all MRI images and sequences.

CONCLUSIONS

Even 1 ml SPIO tracer used for sentinel node procedure impairs the evaluation of breast MRI at the tracer injection site beyond one year of follow-up. No impairment was observed on FFDM/CEM, suggesting that CEM might be a reliable alternative to breast MRI if required.

The Introduction of Magtrace® Lymphatic Tracer for Axillary Sentinel Node Biopsy for Breast Cancer in a Rural Scottish District General Hospital: Initial Experience, Perspectives, Outcomes and Learning Curves

BACKGROUND

Magtrace is a supraparamagnetic iron lymphatic tracer that has had increasing use in sentinel node biopsy (SNB) for breast cancer and has theoretical logistical benefits in centres where nanocolloid use may be associated with such issues. We describe our initial experience with the introduction of Magtrace into our routine practice by dual localisation with nanocolloid, comparing performance, and concordance.

MATERIALS AND METHODS

This was prospective study of the first patients undergoing axillary SNB using Magtrace in a single centre. These patients had dual localisation with nanocolloid and Magtrace. Subjective global assessments of Magtrace and nanocolloid performance as well as objective signal strength and anatomical concordance were compared across multiple timepoints in the operative journey.

RESULTS

A total of 30 consecutive patients underwent SNB within the timeframe of this study. While there were no failed SNB, 8 issues were reported including 4 issues of perceived imperfect localisation on global assessment. No patient had a failed or abandoned SNB, and only 1 case had a potential challenge in subsequent management after histopathological examination of the retrieved nodes. The majority of these issues occurred in the first half of the study period. There was overall weak to moderate positive correlation between Magtrace and nanocolloid signals of the retrieved sentinel nodes (Spearman's ρ = 0.392, P = .043).

CONCLUSION

This study suggests that introducing Magtrace was feasible and safe in the context of a rural breast cancer service. A possible strategy to ameliorate the learning curve associated with these procedures is the routine dual localisation in the initial phases of performing Magtrace localisation.

Assessing the Sentimag system for guiding sentinel node biopsies in patients with breast cancer

INTRODUCTION

Sentinel lymph node biopsy for breast cancer is a method to localize and excise the first draining lymph node from an invasive cancer of the breast. The histopathologic evaluation of the sentinel lymph node is used for predicting recurrence and survival and thus, guiding oncologists for treatment-decision making to administer adjuvant therapies. The ability to identify the sentinel node depends on methods to map lymphatic drainage from the breast to the sentinel node and accurately discriminate that node from other non-sentinel lymph nodes of the axilla.

AREAS COVERED

This review covers the clinical demand for technologies to assist the surgeon in intraoperative lymphatic mapping to specifically identify the sentinel lymph node in patients with breast cancer. Performance characteristics are reviewed for superparamagnetic iron oxide tracers used in lymphatic mapping compared to other current available technologies for lymphatic mapping.

EXPERT OPINION

The Magtrace (superparamagnetic iron oxide tracer) Sentimag (handheld magnetic probe) system is an FDA-approved technology for intraoperative lymphatic mapping to facilitate sentinel lymph node biopsy in breast cancer with technologic performance characteristics that are equivalent to 99Technetium-sulfur colloid. Barriers to broader utilization primarily center around the need for nonmetallic devices to be used for the conduct of surgery, which would interfere with the paramagnetic method for tracer localization.

Performance of a Nonlinear Magnetic Handheld Probe for Intraoperative Sentinel Lymph Node Detection: A Phantom Study

OBJECTIVE

This study investigates the performance of the DiffMag handheld probe (nonlinear magnetometry), to be used for sentinel lymph node detection. Furthermore, the performance of DiffMag is compared with a gamma probe and a first-order magnetometer (Sentimag®, linear magnetometry).

METHODS

The performance of all three probes was evaluated based on longitudinal distance, transverse distance, and resolving power for two tracer volumes. A phantom was developed to investigate the performance of the probes for a clinically relevant situation in the floor of the mouth (FOM).

RESULTS

Considering the longitudinal distance, both DiffMag handheld and Sentimag® probe had comparable performance, while the gamma probe was able to detect at least a factor of 10 deeper. Transverse distances of 13, 11, and 51 mm were measured for the small tracer volume by the DiffMag handheld, Sentimag®, and the gamma probe, respectively. For the large tracer volume this was 21, 18, and 55 mm, respectively. The full width at half maximum, at 7 mm probe height from the phantom surface, was 14, 12, and 18 mm for the small tracer volume and 15, 18, and 25 mm for the large tracer volume with the DiffMag handheld, Sentimag®, and gamma probe, respectively.

CONCLUSIONS

With a high resolving power but limited longitudinal distance, the DiffMag handheld probe seems suitable for detecting SLNs which are in close proximity to the primary tumor. In this study, comparable results were shown using linear magnetometry. The gamma probe reached 10 times deeper, but has a lower resolving power compared with the DiffMag handheld probe.

Ultra-Low Dose of Superparamagnetic Iron Oxide Nanoparticles for Sentinel Lymph Node Detection in Patients with Breast Cancer

BACKGROUND

Sentinel lymph node (SLN) status is pivotal for treatment decision-making in patients with breast cancer. Superparamagnetic iron oxide nanoparticles (SPIO) have been shown to be equivalent to the dual technique with technetium99m (Tc99) and blue dye (BD) for SLN detection. The aim of this study was to determine the feasibility of detecting SLNs using an ultra-low dose of SPIO.

METHOD

Patients planned for breast conserving surgery and SLN biopsy were included. An intradermal injection of 0.1 mL SPIO was administered at the areolar border up to 7 days before surgery. Tc99/BD was administered according to clinical routine. SLNs were detected during surgery using a handheld magnetometer. All nodes with a magnetic and/or radioactive signal, as well as blue or clinically suspicious nodes, were harvested and analyzed.

RESULTS

In 50 patients, SPIO was injected a median of 4 days before surgery. At least one SLN was found in all patients with both methods. A total of 98 SLNs were removed; 90 were detected using SPIO and 88 using Tc99/BD. Of the 90 SLNs detected by SPIO, 80 were Tc99/BD positive (concordance 89%). Histopathological analysis classified 16 patients with tumor cells deposit and 9 with macro-metastasis > 2mm, where one SLN was identified only by the radioactive technique and one only by the magnetic technique.

DISCUSSION

SLN detection using 0.1 mL ultra-low dose SPIO injected intradermally was successful in all patients. A future analysis will determine whether the approach using an ultra-low dose of SPIO injected intradermally will minimize skin staining and MRI artefacts.

New techniques versus standard mapping for sentinel lymph node biopsy in breast cancer: a systematic review and meta-analysis

New tracers for sentinel lymph node biopsy (SLNB), as indocyanine green (ICG), superparamagnetic iron oxide (SPIO) and micro bubbles, have been recently introduced in clinical practice showing promising but variable results. We reviewed the available evidence comparing these new techniques with the standard tracers to evaluate their safety. To identify all available studies, a systematic search was performed in all electronic databases. Data regarding sample size, mean number of SLN harvested for patient, number of metastatic SLN and SLN identification rate of all studies were extracted. No significant differences were found in terms of SLNs identification rates between SPIO, RI and BD but with a higher identification rate with the use of ICG. No significant differences were also found for the number of metastatic lymph nodes identified between SPIO, RI and BD and the mean number of SLNs identified between SPIO and ICG versus conventional tracers. A statistically significant differences in favor of ICG was reported for the comparison between ICG and conventional tracers for the number of metastatic lymph nodes identified. Our meta-analysis demonstrates that the use of both ICG and SPIO for the pre-operative mapping of sentinel lymph nodes in breast cancer treatment is adequately effective.

Safety and Efficacy of Mitoxantrone Hydrochloride Injection for Identification of Axillary Sentinel Lymph Nodes in Patients with Primary Breast Cancer

BACKGROUND

The dual technique using blue dye in combination with a radioisotope is considered the gold standard for identifying sentinel lymph nodes (SLNs) in patients with breast cancer. Unfortunately, not all cancer centres have access to radioactive material, which jeopardizes the SLN identification rate and patient safety.

AIM

We aimed to assess the safety and efficacy of mitoxantrone hydrochloride injection (MHI) for identifying axillary SLNs in patients with primary breast cancer.

PATIENTS AND METHODS

We have conducted a prospective non-randomized analysis of patients diagnosed with invasive breast cancer who agreed to participate in the study between December 2019 and December 2022. We have used the patient's medical records to collect the data. We have used the SLN intraoperative identification rate as a marker for the efficacy of the technique and both the immediate and delayed complication rates and routine blood tests as markers for the safety of the technique.

RESULTS

Out of the 296 patients, 289 (97.6%) had their SLNs identified using MHI, while seven patients (2.3%) had four-node sampling carried out because the SLNs were not identified. Liver functions were not significantly affected by MHI, and there was no technique-related readmission or reported morbidity or mortality.

CONCLUSION

We have found that the MHI technique is still inferior to the combined radioactive directed technique and patent blue V dye in SLN identification. Yet, it may serve as a safe and reliable alternative in cases where the radioactive technique is unavailable.

Axillary sentinel lymph node identification using superparamagnetic iron oxide versus radioisotope in early stage breast cancer: The UK SentiMag trial (SMART study)

BACKGROUND & OBJECTIVES

Sentinel lymph node biopsy (SLNB) is an accurate and reliable method for staging the axilla in early breast cancer. The gold standard technique for localizing the sentinel lymph node (SLN) is the use of radioisotope with or without blue dye. However, this technique has its limitations. Various alternatives have been explored to overcome the disadvantages of the standard SLNB technique and superparamagnetic iron oxide mapping agents have garnered significant attention. The SMART study aims to compare the magnetic technique using the superparamagnetic iron oxide particles (SPIO, Sienna+®) to the radioisotope technique (Tc99) +/- blue dye, for SLN identification in patients with early breast cancer.

METHODS

A prospective, multicenter study was done that recruited 109 clinically node-negative early-stage breast cancer patients from five centres in the United Kingdom (UK). The patients received radioisotope ± blue dye injections, followed by intraoperative injection of magnetic tracer prior to SLNB. The sentinel node identification rate was compared between the magnetic and standard techniques to evaluate detection rate (per patient and per node), non-inferiority and concordance.

RESULTS

Data was analysed for 107 patients. The per patient detection rate was 98.13% (105/107) when using the magnetic tracer and 92.26% (103/107) when using the standard technique. The nodal detection rate was 93.07% (188/202 nodes) when using the magnetic tracer and 96.53% (195/202) when using the standard technique. Of the 31 patients with positive sentinel lymph nodes (SLNs), all 31 (100%) were detected by both techniques.

CONCLUSION

Our study demonstrates that the magnetic technique is a feasible method for SLNB, with an identification rate that is not inferior to the standard technique. The magnetic technique offers a suitable alternative to the standard technique thereby avoiding the need for the complexities of nuclear medicine, the hazards of radiation and the anaphylaxis risk of blue dye.

Use of Superparamagnetic Iron Oxide (SPIO) Versus Conventional Technique in Sentinel Lymph Node Detection for Breast Cancer: A Randomised Controlled Trial

BACKGROUND

The objective of this study is to compare the efficacy of the superparamagnetic iron oxide (SPIO)-guided and standard techniques for sentinel lymph node (SLN) detection in early breast cancer. Multiple inferiority trials have concluded the non-inferiority of SPIO to the conventional radioisotope technique, with or without blue dye, in detecting SLNs.

PATIENTS AND METHODS

From July 2018 to August 2022, patients clinically diagnosed with node-negative invasive breast cancer were randomised into the study group (SPIO) and control group (radioisotope and blue dye). Patient data and disease characteristics were prospectively collected. SLN detection rates were compared between the two groups.

RESULTS

A total of 282 patients undergoing 288 sentinel lymph node biopsy (SLNB) procedures were recruited, and 144 SLNB procedures were randomised into each group. The baseline patient and disease characteristics were comparable. SLN localisation failed in one patient in each group; the success rate of SLNB was 99.3%. The SPIO group demonstrated a higher mean number of SLNs harvested (3.3 versus 2.8, p = 0.039) and longer mean procedure duration (33.1 min versus 22.3 min, p = 0.01) than the control group did. In the study group, the concordance rates per patient and node were 99.3% and 94.6%, respectively. Sixty-seven positive SLNs were detected in 37 patients. The concordance rates per malignant SLNB procedure and positive SLN were 97.3% and 96.8%, respectively.

CONCLUSION

Single-tracer SPIO-guided SLNB was non-inferior to the dual technique (radioisotope and blue dye) and could safely replace the gold standard for SLN mapping in early breast cancer.

Combined use of magnetic seed and tracer in breast conserving surgery with sentinel lymph node biopsy for non-palpable breast lesions: A pilot study describing pitfalls and solutions

BACKGROUNDS

Traditionally, breast conserving surgery for non-palpable breast cancer is guided by wire or radioactive seed and radioactive tracer for sentinel lymph node biopsy (SLNB). Alternatively, a stain-less magnetic seed and superparamagnetic iron oxide tracer (SPIO) can be combined as a radioactive-free technique. The aim of this study was to define the pitfalls we encountered during implementation of this combined technique and provide solutions resulting in an instruction manual for a radio-active free procedure.

METHODS

Between January and March 2021, seventeen consecutive patients with cN0 non-palpable breast cancer were included. The magnetic seed was placed to localize the lesion and SPIO was used to identify the sentinel lymph node (SLN). A lymphoscintigraphy with Technetium-99m nano colloid was performed concomitantly in all patients as a control procedure for SPIO. Surgical outcomes are reported, including problems with placing and retrieval of the seed and SPIO and corresponding solutions.

RESULTS

Surgical excision was successful with invasive tumor-free margins in all patients. SLN detection was successful in 82% patients when compared to Technetium-99m. The most challenging issue was an overlapping magnetic signal of the seed and SPIO. Solutions are provided in detail.

CONCLUSIONS

Combined use of magnetic seed and SPIO for wide local excision and SLNB patients with non-palpable breast lesions appeared challenging due to overlapping magnetic signals. After multiple adaptations, the protocol proved to be feasible with an added advantage of eliminating the use of radioisotopes. We described the pitfalls and solutions resulting in an instruction manual for a totally radioactive-free procedure.

Is Sentinel Lymph Node Biopsy Necessary in Patients who Undergo Prophylactic Mastectomy?

BACKGROUND

Over the last decade, rates of risk-reducing prophylactic mastectomy (PM) have risen dramatically. A topic of debate regarding the procedure is whether to use sentinel lymph node biopsy (SLNB) at the time of PM and what factors might predict for such need. In order to assess the rate of identifying presence of occult invasive breast cancer in the PM specimen, we performed a retrospective review of the pathology findings from a single-surgeon case-series of PM.

METHODS

Patients undergoing PM between January 2013 and June 2019 at Orlando Health Cancer Institute were identified for a retrospective chart review. Demographic, clinical, and histopathological data from the surgical procedure were collected and analyzed for the incidence of occult invasive breast cancer in the PM specimen.

RESULTS

A total of 146 consecutive patients with PM were identified; 120 (82.2%) underwent contralateral PM (CPM) and 26 (17.8%) underwent bilateral PM (BPM). Final pathology of the 172 PM specimens identified 4 (3.3%) with lobular carcinoma in situ, 3 (2.5%) with atypical ductal hyperplasia, and 2 (1.7%) with atypical lobular hyperplasia and 2 (1.7%) with intraductal papilloma. No invasive malignancy was detected in any of the 172 PM specimens.

CONCLUSIONS

The absence of occult invasive carcinoma in 172 consecutive PM specimens suggests a limited clinical utility in routinely performing SLNB in this setting. This study also suggests that use of preoperative breast MRI imaging could offer a potential non-invasive tool to detect occult malignancy and select patients who can safely undergo omission of SLNB at the time of PM.

Evolution and refinement of magnetically guided sentinel lymph node detection in breast cancer: meta-analysis

BACKGROUND

Superparamagnetic iron oxide nanoparticles (SPIO) have been used as a tracer for sentinel lymph node (SLN) localization in breast cancer, demonstrating comparable performance to the combination of radioisotope (RI) and blue dye (BD).

METHODS

A systematic literature search and meta-analysis with subgroup and meta-regression analysis were undertaken to update the available evidence, assess technique evolution, and define knowledge gaps. Recommendations were made using the GRADE approach.

RESULTS

In 20 comparative studies, the detection rate was 97.5 per cent for SPIO and 96.5 per cent for RI ± BD (risk ratio 1.006, 95 per cent c.i. 0.992 to 1.019; P = 0.376, high-certainty evidence). Neoadjuvant therapy, injection site, injection volume or nodal metastasis burden did not affect the detection rate, but injection over 24 h before surgery increased the detection rate on meta-regression. Concordance was 99.0 per cent and reverse concordance 97.1 per cent (rate difference 0.003, 95 per cent c.i. -0.009 to 0.015; P = 0.656, high-certainty evidence). Use of SPIO led to retrieval of slightly more SLNs (pooled mean 1.96 versus 1.89) with a higher nodal detection rate (94.1 versus 83.5 per cent; RR 1.098, 1.058 to 1.140; P < 0.001; low-certainty evidence). In meta-regression, injection over 24 h before surgery increased the SPIO nodal yield over that of RI ± BD. The skin-staining rate was 30.8 per cent (very low-certainty evidence), and possibly prevented with use of smaller doses and peritumoral injection.

CONCLUSION

The performance of SPIO is comparable to that of RI ± BD. Preoperative injection increases the detection rate and nodal yield, without affecting concordance. Whether skin staining and MRI artefacts are reduced by lower dose and peritumoral injection needs to be investigated.

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

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 cm² (p = 0.56), while 51 (25.0%) had a BD stain with a median size of 8.5 cm² (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 cm², respectively. For BD, the incidence was 14 (6.3%, p = 0.13), and the median size was 3.5 cm² (p = 0.18). There was, therefore, no statistically significant difference in the incidence or size of skin staining between SPIO and BD over time.

The Application of Magnetic Nanoparticles for Sentinel Lymph Node Detection in Clinically Node-Negative Breast Cancer Patients: A Systemic Review and Meta-Analysis

Superparamagnetic iron oxide (SPIO), an alternative mapping agent, can be used to identify sentinel lymph nodes in patients with clinically node-negative breast cancer. However, its performance in comparison with the standard method, using a radioisotope (technetium-99 m, Tc) alone or in combination with blue dye, remains controversial. Hence, a systematic review and meta-analysis were conducted to evaluate the diagnostic accuracy of SPIO and its clinical impact in the management of breast cancer. The PubMed, Embase, and Cochrane databases were comprehensively searched from inception to 1 May 2022. Cohort studies regarding the comparison of SPIO with standard methods for sentinel lymph node identification were included. A total of 19 prospective cohort studies, which collectively included 2298 clinically node-negative breast cancer patients undergoing sentinel lymph node identification through both the standard method and SPIO, were identified. The detection rate for sentinel lymph nodes (RR, 1.06; 95% CI, 1.05−1.08; p < 0.001) was considerably higher in the SPIO cohorts than in the standard method cohorts, although this difference was not significant in detected patients, patients with positive sentinel lymph nodes, or positive sentinel lymph nodes. Compared with the standard method, the SPIO method could be considered as an alternative standard of care for sentinel lymph node detection in patients with clinically node-negative breast cancer.

The Advances and Biomedical Applications of Imageable Nanomaterials

Nanomedicine shows great potential in screening, diagnosing and treating diseases. However, given the limitations of current technology, detection of some smaller lesions and drugs’ dynamic monitoring still need to be improved. With the advancement of nanotechnology, researchers have produced various nanomaterials with imaging capabilities which have shown great potential in biomedical research. Here, we summarized the researches based on the characteristics of imageable nanomaterials, highlighted the advantages and biomedical applications of imageable nanomaterials in the diagnosis and treatment of diseases, and discussed current challenges and prospects.

Efficacy and Safety of Mitoxantrone Hydrochloride Injection for Tracing Axillary Sentinel Nodes in Breast Cancer: A Self-Controlled Clinical Trial

Background

Mitoxantrone hydrochloride injection for tracing (MHI), a new strategy to identify lymph nodes, has not been tested for axillary node staging in breast cancer. This multicenter, self-controlled, non-inferiority trial aimed to evaluate MHI’s efficacy and safety in sentinel lymph node biopsy (SLNB).

Methods

The trial was conducted across seven hospitals from December 2019 to December 2020. Patients with early-stage breast cancer received MHI and technetium-99m (99mTc) during the surgery. Sentinel node detection rates were compared between MHI and 99mTc to evaluate non-inferiority and concordance. Non-inferiority was valid if the lower limit of the 95% CI of sentinel node relative detection rate difference was ≥−5%.

Results

SLN relative detection rate of MHI was 97.31% (362/372). Of the SLNs, 79.69% (871/1093) were co-detected by both tracers. Of the patients, 4.13% (16/387) had adverse events and recovered during the follow-up.

Conclusions

MHI is a lymphatic tracer with comparable efficacy to radionuclides and can be used alone or in combination with radioactive substances for SLNB.

Clinical Trial Registration

http://www.chinadrugtrials.org.cn, CTR20192435.

Feasibility of Magnetic Technique for Axillary Staging after Neoadjuvant Therapy in Breast Cancer Patients

PURPOSE

Optimal axillary staging after neoadjuvant chemotherapy (NAC) in node-negative breast cancer is an area of controversy. Sentinel node biopsy with Technetium-sulphur colloid (99m Tc) alone or with blue dye is the recommended technique for evaluating axilla in these patients. However, this technique has drawbacks such as limited access to nuclear departments and timing limitations related to Tc injection exposing patients to unnecessary radiation. Superparamagnetic iron oxide nanoparticles (SPIO) may represent a valid option for SLN biopsy. In this study, we assessed the feasibility of the magnetic technique (Sentimag) with combination of isosulfan blue dye in breast cancer patients who received NAC.

METHODS

The study sample consisted of 54 female breast cancer patients who received NAC. Sentinel node localization was performed using magnetic technique and blue dye. Sentinel node identification rate (IFR) of magnetic technique was calculated and postoperative complications were assessed.

RESULTS

Sentinel lymph node was detected in 52 patients with Sentimag method (identification rate = 96.3%, 95% CI: 87.4-98.9%). Blue dye was successful to find SLN in 38 patients (identification rate = 70%). The most common histologic type was invasive ductal (n = 51; 94.4%). Mean tumor size was 2.1 cm after NAC. Most of patients had T2 (n = 30; 55.5%) and HER2 + positive (n = 49; 90.7%) cancer.

CONCLUSION

Sentimag which is a magnetic technique appears to be safe, easy to perform with minimal adverse effects, may be an alternative and accurate technique in patients with NAC, especially in breast units where nuclear medicine unit is not available.

Supplemental data for this article is available online at https://doi.org/10.1080/08941939.2022.2038737 .

A Propensity Score Matched Analysis of Superparamagnetic Iron Oxide versus Radioisotope Sentinel Node Biopsy in Breast Cancer Patients after Neoadjuvant Chemotherapy

The standard method for nodal staging in breast cancer (BC) patients after neoadjuvant chemotherapy (NAC) is sentinel lymph node biopsy (SLNB) with a radioisotope (RI) injection. However, SLNB after NAC results in high false-negative rates (FNR), and the RI method is restricted by nuclear medicine unit dependency. These limitations resulted in the development of the superparamagnetic iron oxide (SPIO) method, reducing FNR and presenting a comparable detection rate. This bi-institutional cohort comparison study aimed to assess the efficacy of SPIO and radioisotope SNLB in BC patients after NAC using Propensity Score Matching (PSM) analysis. The study group comprised 508 patients who underwent SLNB after NAC for ycT1-4N0M0 BC between 2013 and 2021 in two high volume centers. Data were retrieved from prospectively conducted databases. In the SPIO group, the median of retrieved sentinel lymph nodes (SLNs) was significantly higher than in the RI group (3 vs. 2; p < 0.0001). The SPIO method was associated with a significantly higher chance of retrieving at least three lymph nodes when compared to the RI method (71% vs. 11.3%; p < 0.0001). None of the analyzed demographic and clinical variables had a statistically significant influence on the efficacy of SLNs retrieval in the RI group, while in the SPIO group, patients with ≥three harvested SLNs had lower weight and decreased BMI. Based on this PSM analysis, SPIO-guided SLNB allowed the efficient retrieval and detection of SLNs in BC patients after NAC compared to RI.

A Propensity Score Matched Analysis of Superparamagnetic Iron Oxide versus Radioisotope Sentinel Node Biopsy in Breast Cancer Patients after Neoadjuvant Chemotherapy

Simple Summary

This Propensity Score Matched Analysis aimed to assess the efficacy of superparamagnetic iron oxide (SPIO) and radioisotope sentinel lymph node biopsy (SNLB) in breast cancer (BC) patients after neoadjuvant chemotherapy (NAC). One hundred and twenty-four patients were eligible for final analysis. In the SPIO group, the median of retrieved sentinel lymph nodes (SLNs) was significantly higher than in the RI group. The SPIO method was associated with a significantly higher chance of retrieving at least three SLNs when compared to the RI method. SPIO-guided SLNB allows efficient retrieval and detection of SLNs in BC patients after NAC when compared to RI.

Abstract

The standard method for nodal staging in breast cancer (BC) patients after neoadjuvant chemotherapy (NAC) is sentinel lymph node biopsy (SLNB) with a radioisotope (RI) injection. However, SLNB after NAC results in high false-negative rates (FNR), and the RI method is restricted by nuclear medicine unit dependency. These limitations resulted in the development of the superparamagnetic iron oxide (SPIO) method, reducing FNR and presenting a comparable detection rate. This bi-institutional cohort comparison study aimed to assess the efficacy of SPIO and radioisotope SNLB in BC patients after NAC using Propensity Score Matching (PSM) analysis. The study group comprised 508 patients who underwent SLNB after NAC for ycT1-4N0M0 BC between 2013 and 2021 in two high volume centers. Data were retrieved from prospectively conducted databases. In the SPIO group, the median of retrieved sentinel lymph nodes (SLNs) was significantly higher than in the RI group (3 vs. 2; p < 0.0001). The SPIO method was associated with a significantly higher chance of retrieving at least three lymph nodes when compared to the RI method (71% vs. 11.3%; p < 0.0001). None of the analyzed demographic and clinical variables had a statistically significant influence on the efficacy of SLNs retrieval in the RI group, while in the SPIO group, patients with ≥three harvested SLNs had lower weight and decreased BMI. Based on this PSM analysis, SPIO-guided SLNB allowed the efficient retrieval and detection of SLNs in BC patients after NAC compared to RI.

Breast MRI in patients after breast conserving surgery with sentinel node procedure using a superparamagnetic tracer

BACKGROUND

A procedure for sentinel lymph node biopsy (SLNB) using superparamagnetic iron-oxide (SPIO) nanoparticles and intraoperative sentinel lymph node (SLN) detection was developed to overcome drawbacks associated with the current standard-of-care SLNB. However, residual SPIO nanoparticles can result in void artefacts at follow-up magnetic resonance imaging (MRI) scans. We present a grading protocol to quantitatively assess the severity of these artefacts and offer an option to minimise the impact of SPIO nanoparticles on diagnostic imaging.

METHODS

Follow-up mammography and MRI of two patient groups after a magnetic SLNB were included in the study. They received a 2-mL subareolar dose of SPIO (high-dose, HD) or a 0.1-mL intratumoural dose of SPIO (low-dose, LD). Follow-up mammography and MRI after magnetic SLNB were acquired within 4 years after breast conserving surgery (BCS). Two radiologists with over 10-year experience in breast imaging assessed the images and analysed the void artefacts and their impact on diagnostic follow-up.

RESULTS

A total of 19 patients were included (HD, n = 13; LD, n = 6). In the HD group, 9/13 patients displayed an artefact on T1-weighted images up to 3.6 years after the procedure, while no impact of the SPIO remnants was observed in the LD group.

CONCLUSIONS

SLNB using a 2-mL subareolar dose of magnetic tracer in patients undergoing BCS resulted in residual artefacts in the breast in the majority of patients, which may hamper follow-up MRI. This can be avoided by using a 0.1-mL intratumoural dose.

Application of Magnetic Nanoparticles for Rapid Detection and In Situ Diagnosis in Clinical Oncology

Screening, monitoring, and diagnosis are critical in oncology treatment. However, there are limitations with the current clinical methods, notably the time, cost, and special facilities required for radioisotope-based methods. An alternative approach, which uses magnetic beads, offers faster analyses with safer materials over a wide range of oncological applications. Magnetic beads have been used to detect extracellular vesicles (EVs) in the serum of pancreatic cancer patients with statistically different EV levels in preoperative, postoperative, and negative control samples. By incorporating fluorescence, magnetic beads have been used to quantitatively measure prostate-specific antigen (PSA), a prostate cancer biomarker, which is sensitive enough even at levels found in healthy patients. Immunostaining has also been incorporated with magnetic beads and compared with conventional immunohistochemical methods to detect lesions; the results suggest that immunostained magnetic beads could be used for pathological diagnosis during surgery. Furthermore, magnetic nanoparticles, such as superparamagnetic iron oxide nanoparticles (SPIONs), can detect sentinel lymph nodes in breast cancer in a clinical setting, as well as those in gallbladder cancer in animal models, in a surgery-applicable timeframe. Ultimately, recent research into the applications of magnetic beads in oncology suggests that the screening, monitoring, and diagnosis of cancers could be improved and made more accessible through the adoption of this technology.

Sentinel lymph node biopsy with a handheld cordless magnetic probe following preoperative MR lymphography using superparamagnetic iron oxide for clinically N0 early oral cancer: A feasibility study

PURPOSE

Radioisotope (RI) tracers are generally used for preoperative mapping of sentinel lymph node (SLN) and intraoperative detection with a portable γ probe. However, the use of RI has several limitations. Therefore, a method without RI is required for the widespread application of SLN biopsy. The purpose of this study was to evaluate the feasibility of SLN biopsy with a handheld cordless magnetic probe following magnetic resonance lymphography (MRL) using superparamagnetic iron oxide (SPIO) and for clinically N0 early oral cancer.

MATERIALS AND METHODS

MRL using SPIO and SLNB with the handheld cordless magnetic probe were performed for 27 patients with clinically N0 early oral cancer.

RESULTS

In all 27 patients (100%), SLNs were detected by MRL, and the total and mean number of SLNs were 73 and 2.7, respectively. All SLNs identified by MRL were detectable using the magnetic probe in all patients.

CONCLUSIONS

SLNB with handheld cordless magnetic probe following preoperative SLN mapping by MRL using SPIO is feasible, without RI use, for neck management in cases of clinically N0 early oral cancer.

Optimization of SPIO Injection for Sentinel Lymph Node Dissection in a Rat Model

The magnetic technique, consisting of a magnetic tracer and a handheld magnetometer, is a promising alternative technique for sentinel lymph node dissection (SLND) and was shown to be non-inferior to the standard technique in terms of identification rates. In this study, injection characteristics (iron dose, dilution, time course and massaging) were evaluated to optimize magnetic tracer uptake in the sentinel lymph nodes (SLN) in a rat hindleg model. 202 successful SLNDs were performed. Iron uptake in the SLN is proportional (10% utilization rate) to the injection dose between 20 and 200 μg, showing a plateau uptake of 80 μg in the SLN around 1000 μg injection. Linear regression showed that time had a higher impact than dilution, on the SLN iron uptake. Massaging showed no significant change in iron uptake. The amount of residual iron at the injection site was also proportional to the injection dose without any plateau. Time was a significant factor for wash-out of residual iron. From these results, preoperative injection may be advantageous for SLN detection as well as reduction in residual iron at the injection site by potential decrease in required injection dose.

Optimization of SPIO Injection for Sentinel Lymph Node Dissection in a Rat Model

Simple Summary

In this study, the following injection characteristics were evaluated to optimize magnetic tracer uptake in the sentinel lymph nodes (SLN) in a rat hindleg model: (a) iron dose, (b) effect of dilution, (c) effect of injecting at different time courses and (d) effect of massaging the injection site. In conclusion, injection dose and time were primary factors for the SLN iron uptake. The result from this study will provide a background for magnetic procedures.

Abstract

The magnetic technique, consisting of a magnetic tracer and a handheld magnetometer, is a promising alternative technique for sentinel lymph node dissection (SLND) and was shown to be non-inferior to the standard technique in terms of identification rates. In this study, injection characteristics (iron dose, dilution, time course and massaging) were evaluated to optimize magnetic tracer uptake in the sentinel lymph nodes (SLN) in a rat hindleg model. 202 successful SLNDs were performed. Iron uptake in the SLN is proportional (10% utilization rate) to the injection dose between 20 and 200 μg, showing a plateau uptake of 80 μg in the SLN around 1000 μg injection. Linear regression showed that time had a higher impact than dilution, on the SLN iron uptake. Massaging showed no significant change in iron uptake. The amount of residual iron at the injection site was also proportional to the injection dose without any plateau. Time was a significant factor for wash-out of residual iron. From these results, preoperative injection may be advantageous for SLN detection as well as reduction in residual iron at the injection site by potential decrease in required injection dose.

Pharmacokinetics of Single Domain Antibodies and Conjugated Nanoparticles Using a Hybrid near Infrared Method

Iron oxide nanoparticles and single domain antibodies from camelids (VHHs) have been increasingly recognized for their potential uses for medical diagnosis and treatment. However, there have been relatively few detailed characterizations of their pharmacokinetics (PK). The aim of this study was to develop imaging methods and pharmacokinetic models to aid the future development of a novel family of brain MRI molecular contrast agents. An efficient near-infrared (NIR) imaging method was established to monitor VHH and VHH conjugated nanoparticle kinetics in mice using a hybrid approach: kinetics in blood were assessed by direct sampling, and kinetics in kidney, liver, and brain were assessed by serial in vivo NIR imaging. These studies were performed under "basal" circumstances in which the VHH constructs and VHH-conjugated nanoparticles do not substantially interact with targets nor cross the blood brain barrier. Using this approach, we constructed a five-compartment PK model that fits the data well for single VHHs, engineered VHH trimers, and iron oxide nanoparticles conjugated to VHH trimers. The establishment of the feasibility of these methods lays a foundation for future PK studies of candidate brain MRI molecular contrast agents.

A complete magnetic sentinel lymph node biopsy procedure in oral cancer patients: A pilot study

OBJECTIVES

To assess the feasibility and merits of a complete magnetic approach for a sentinel lymph node biopsy (SLNB) procedure in oral cancer patients.

MATERIALS AND METHODS

This study included ten oral cancer patients (stage cT1-T2N0M0) scheduled for elective neck dissection (END). Superparamagnetic iron oxide nanoparticles (SPIO) were administered peritumorally prior to surgery. A preoperative MRI was acquired to identify lymph nodes (LNs) with iron uptake. A magnetic detector was used to identify magnetic hotspots prior, during, and after the SLNB procedure. The resected sentinel LNs (SLNs) were evaluated using step-serial sectioning, and the neck dissection specimen was assessed by routine histopathological examination. A postoperative MRI was acquired to observe any residual iron.

RESULTS

Of ten primary tumors, eight were located in the tongue, one floor-of-mouth (FOM), and one tongue-FOM transition. SPIO injections were experienced as painful by nine patients, two of whom developed a tongue swelling. In eight patients, magnetic SLNs were successfully detected and excised during the magnetic SLNB procedure. During the END procedure, additional magnetic SLNs were identified in three patients. Histopathology confirmed iron deposits in sinuses of excised SLNs. Three SLNs were harboring metastases, of which one was identified only during the END procedure. The END specimens revealed no further metastases.

CONCLUSION

A complete magnetic SLNB procedure was successfully performed in eight of ten patients (80% success rate), therefore the procedure seems feasible. Recommendations for further investigation are made including: use of anesthetics, magnetic tracer volume, planning preoperative MRI, comparison to conventional technique and follow-up.

Introducing SentiMag in a rural setting: A 5-year experience

BACKGROUND

The Sentimag device is a probe that contains a sensitive magnetometer which detects either an implantable magnetic marker (MagSeed) or an infectable superparamagnetic ironoxide nanoparticle tracer (MagTrace). MagSeed is used to localise impalpable breast lesions; MagTrace is used to identify sentinel lymph nodes. In Australasia, Sentinel lymph node (SLN) biopsy, using radioactive colloid injection, is a mainstay of prognostication in breast surgery in patients with a clinically negative axilla. In addition, radioactive seeds or hookwires have been used to detect impalpable breast lesions. Gisborne Hospital has been using the SentiMag device since June 2016 to both identify sentinel lymph nodes (Magtrace) and impalpable tumours (Magseed). This study gives perspective over more than 5 years on how this new technology can benefit patients and clinicians in the rural setting.

METHODS

Patient data had been collected by the operative surgeon prospectively and corroborated with the coding department. Consecutive cases performed by a single surgeon were included in this study. Inclusion criteria were: (1) any patient who needed localisation of an impalpable breast lesion; (2) any patient who needed a sentinel lymph node biopsy; (3) cases were collected from January 2013 with the large majority of cases were collected between January 2015 and Jan 2020. Comparisons were made between patients with different localisation methods. Basic demographics were collected at the time of the surgery and outcomes then recorded. Staging, lymph node status, lymph node detection rates and complications were collected. Mode of tumour and sentinel node location was recorded. Financial data was collected from administrative staff via receipts and invoices of purchases to the hospital.

RESULTS

Of the 125 patients included in this study: 23 underwent magnetic seed insertion; 15 underwent a hookwire insertion; 45 cases used MagTrace injection; 71 cases used radioactive colloid injection. There was a significantly higher detection rate of two or more sentinel nodes in the SentiMag group. (91% vs. 71.8%, p = 0.01). Neither complication rates, nor cancer detection rates were significantly different. Eighty-four (67.2%) cases did not require tumour location.

CONCLUSION

SentiMag is safe to use in a rural setting. Using the SentiMag system can simplify care for patients and surgeons and was shown to be cost effective in our hospital.

Superparamagnetic Iron Oxide for Identifying Sentinel Lymph Node in Breast Cancer after Neoadjuvant Chemotherapy: Feasibility Study

Sentinel lymph node biopsy (SLNB) is a well-established procedure for staging clinically node-negative early breast cancer (BC). Superparamagnetic iron oxide (SPIO) demonstrated efficacy for nodal identification using a magnetic probe after local retroaeroal interstitial injection. Its benefits lie in its flexibility, which is an essential property in the global setting, where access to the isotope is difficult. To the best of our knowledge, this is the first study to evaluate the feasibility and safety of the SPIO for SLNB in BC patients treated with neoadjuvant chemotherapy (NAC). Seventy-four female patients were included. The median time of lymph node retrieval was 20 min. The median number of resected sentinel nodes (SNs) was 4. SN was detected in all patients. No serious adverse event was observed. SPIO in identifying SN in BC patients after NAC is feasible and oncologically safe.

Superparamagnetic Iron Oxide for Identifying Sentinel Lymph Node in Breast Cancer after Neoadjuvant Chemotherapy: Feasibility Study

Sentinel lymph node biopsy (SLNB) is a well-established procedure for staging clinically node-negative early breast cancer (BC). Superparamagnetic iron oxide (SPIO) demonstrated efficacy for nodal identification using a magnetic probe after local retroaeroal interstitial injection. Its benefits lie in its flexibility, which is an essential property in the global setting, where access to the isotope is difficult. To the best of our knowledge, this is the first study to evaluate the feasibility and safety of the SPIO for SLNB in BC patients treated with neoadjuvant chemotherapy (NAC). Seventy-four female patients were included. The median time of lymph node retrieval was 20 min. The median number of resected sentinel nodes (SNs) was 4. SN was detected in all patients. No serious adverse event was observed. SPIO in identifying SN in BC patients after NAC is feasible and oncologically safe.

MR lymphography with superparamagnetic iron oxide for sentinel lymph node mapping of N0 early oral cancer: A pilot study

OBJECTIVES

The purpose of this pilot study was to evaluate the usefulness of magnetic resonance lymphography (MRL) with superparamagnetic iron oxide (SPIO) in sentinel lymph node (SLN) mapping of clinically N0 early oral cancer, and to conduct a comparative study of this MRL with CT lymphography (CTL).

METHODS

CTL and MRL were performed for SLN mapping before surgery for 20 patients with clinically N0 early oral cancer. The detection rate, number, and location of SLNs in CTL and MRL were evaluated. Furthermore, optimal scanning/imaging timing in MRL was examined.

RESULTS

SLNs were detected by CTL in 18 (90%) patients, and the total and mean number of SLN were 35 and 1.8, respectively. All SLNs could be detected 2 min and 3.5-5 min after contrast medium injection. In all patients, SLNs were detected by MRL at 10 min after SPIO injection, and the total and mean number of SLN was 53 and 2.7, respectively. MRL at 30 min after the injection showed additional 18 secondary lymph nodes.

CONCLUSION

MRL with SPIO is safe and useful imaging for the detection of SLNs in clinically N0 early oral cancer, and the optimal imaging timing is 10 min after SPIO injection.

Mapping sentinel lymph nodes in cutaneous melanoma: a vast array of perioperative imaging modalities

Sentinel lymph node biopsy (SLNB) is a decisive step in the staging process of melanoma, critically impacting patients' oncological outcome and driving the decision-making process. SLNB limits the extent of the dissection in cases where no metastases are found. Conversely, when metastases are detected, SLNB has the potential to improve regional control of the disease when complete lymphadenectomy or early administration of adjuvant treatment are indicated. Thus, accurately identifying sentinel lymph nodes represents an important prognostic factor. Several strategies have been studied, including novel procedures that are not commonly used in the clinical setting. This review highlights the different tracers, preoperative and intraoperative imaging modalities studied to perform SLNB in cutaneous melanoma. The development of innovative modalities has been fueled by a need to optimize current approaches, offering new alternatives that can overcome some of the limitations of the standard method.

A single-center, self-controlled, phase I clinical trial of mitoxantrone hydrochloride injection for lymph tracing for sentinel lymph node identification of breast cancer

Background

Mitoxantrone hydrochloride injection for lymph tracing (MHI) is a novel lymphatic tracer for sentinel lymph node (SLN) in patients with early breast cancer but exhibited remarkable liver, kidney, and hematologic toxicities in previous studies. Here, the pharmacokinetics and pharmacodynamics profiles of MHI were evaluated to surmise safety and tolerability.

Methods

Phase 1 open-label, single center, and dose escalation study was performed. Ten patients with invasive breast cancer received 0.5, 1.0, or 2.0 mL of MHI into the breast tissues surrounding the tumor for lymphatic mapping. All of these patients were injected with 2 mCi nuclide-labeled sulfur colloid as a self-control 24 to 48 hours before surgery. Safety was assessed by the incidence of adverse events graded by the National Cancer Institute Common Terminology Criteria, version 4.0.3 (CTCAE4.0.3). Blood samples for pharmacokinetic analyses were collected before and after administration at 15, 30, 60, 120, and 240 min of the injection of MHI.

Results

Up to the cutoff date of the study (Aug 8, 2018), no dose-limiting toxic effects or obvious allergic reactions were observed. Only one case of an adverse event was certainly related to MHI, where it caused blue discoloration of the local skin over the injection site after the operation, but this stain gradually went away. The peak level of MHI was achieved after 15-30 min post injection and completely eliminated from the plasma after 60 min. There were no significant differences in the number of lymph nodes detected by MHI and radioactive colloid. Only one patient with lymph node macrometastases had no SLN detected by either the radioactive colloid or the MHI.

Conclusions

At a dose of up to 2.0 mL, MHI was well tolerated and safe for conducting SLN biopsies in patients with breast cancer. Although there was a case with blue discoloration of the local skin over the injection site after the operation, and remained for a short period of time, but the overall safety was acceptable. Here, we approached a novel SLN tracing slant; however, more investigations of MHI should be performed for further evaluations. (Chinadrugtrials.org.cn number: CXHL1301201, Date of registration: October 12, 2015.).

Optimizing Dose and Timing in Magnetic Tracer Techniques for Sentinel Lymph Node Detection in Early Breast Cancers: The Prospective Multicenter SentiDose Trial

Simple Summary

Superparamagnetic iron oxide (SPIO) nanoparticles have comparable performance to the combination of radioisotope and blue dye (RI + BD) for sentinel lymph node (SLN) biopsy in breast cancer. In this multicenter prospective study, lower SPIO doses (undiluted 1.5 vs. 1.0 mL) in different timeframes (perioperative vs. 1–7 days preoperative) and injection sites (subareolar vs. peritumoral) were compared to the previous standard (diluted 2.0 mL perioperatively) from the earlier Nordic trial. RI + BD were co-administered as background. In total, 534 patients were analyzed. SPIO SLN detection rates were similar (97.5% vs. 100% vs. 97.6%, p = 0.11) and respectively non-inferior to the dual technique. Significantly more SLNs were retrieved in the preoperative 1.0 mL cohort compared with 1.5 mL and the Nordic cohorts (2.18 vs. 1.85 vs. 1.83, p = 0.003). Thus, SPIO at 1.5 and 1.0 mL was non-inferior to both Sienna+^® and the dual technique for SLN detection.

Abstract

Superparamagnetic iron oxide nanoparticles (SPIO) are non-inferior to radioisotope and blue dye (RI + BD) for sentinel lymph node (SLN) detection. Previously, 2 mL SPIO (Sienna+^®) in 3 mL NaCl was used. In this dose-optimizing study, lower doses of a new refined SPIO solution (Magtrace^®) (1.5 vs. 1.0 mL) were tested in different timeframes (0–24 h perioperative vs. 1–7 days preoperative) and injections sites (subareolar vs. peritumoral). Two consecutive breast cancer cohorts (n = 328) scheduled for SLN-biopsy were included from 2017 to 2019. All patients received isotope ± blue dye as back-up. SLNs were identified primarily with the SentiMag^® probe and thereafter a gamma-probe. The primary endpoint was SLN detection rate with SPIO. Analyses were performed as a one-step individual patient-level meta-analysis using patient-level data from the previously published Nordic Trial (n = 206) as a third, reference cohort. In 534 patients, the SPIO SLN detection rates were similar (97.5% vs. 100% vs. 97.6%, p = 0.11) and non-inferior to the dual technique. Significantly more SLNs were retrieved in the preoperative 1.0 mL cohort compared with 1.5 and the 2.0 mL cohorts (2.18 vs. 1.85 vs. 1.83, p = 0.003). Lower SPIO volumes injected up to 7 days before the operation have comparable efficacy to standard SPIO dose and RI + BD for SLN detection.

Optimizing Dose and Timing in Magnetic Tracer Techniques for Sentinel Lymph Node Detection in Early Breast Cancers: The Prospective Multicenter SentiDose Trial

Superparamagnetic iron oxide nanoparticles (SPIO) are non-inferior to radioisotope and blue dye (RI + BD) for sentinel lymph node (SLN) detection. Previously, 2 mL SPIO (Sienna+^®) in 3 mL NaCl was used. In this dose-optimizing study, lower doses of a new refined SPIO solution (Magtrace^®) (1.5 vs. 1.0 mL) were tested in different timeframes (0-24 h perioperative vs. 1-7 days preoperative) and injections sites (subareolar vs. peritumoral). Two consecutive breast cancer cohorts (n = 328) scheduled for SLN-biopsy were included from 2017 to 2019. All patients received isotope ± blue dye as back-up. SLNs were identified primarily with the SentiMag^® probe and thereafter a gamma-probe. The primary endpoint was SLN detection rate with SPIO. Analyses were performed as a one-step individual patient-level meta-analysis using patient-level data from the previously published Nordic Trial (n = 206) as a third, reference cohort. In 534 patients, the SPIO SLN detection rates were similar (97.5% vs. 100% vs. 97.6%, p = 0.11) and non-inferior to the dual technique. Significantly more SLNs were retrieved in the preoperative 1.0 mL cohort compared with 1.5 and the 2.0 mL cohorts (2.18 vs. 1.85 vs. 1.83, p = 0.003). Lower SPIO volumes injected up to 7 days before the operation have comparable efficacy to standard SPIO dose and RI + BD for SLN detection.

Effects of iron oxide particles on MRI and mammography in breast cancer patients after a sentinel lymph node biopsy with paramagnetic tracers

OBJECTIVE

The aim of this study is to evaluate the effect of iron oxide particle deposition on follow-up mammograms and MRI examinations of patients who underwent sentinel lymph node detection with iron oxide particles.

MATERIALS AND METHODS

Two hundred and eighteen patients who had sentinel lymph node biopsy (SLNB) with iron oxide particles were evaluated. Follow-up MRI and mammography were available in 36 and 69 cases respectively. MRI examinations were evaluated for ferromagnetic artifacts that were graded as follows: 0 = No artifact, 1 = Focal area, 2 = Segmental and 3 = Regional signal void artifact. Mammography artifacts were evaluated for the presence of dense particles. Pearson's chi-square test was used for statistical analyses and P < 0.05 was accepted as significant.

RESULTS

MRI artifact grading was as follows: Grade 0: 11 (30.6%), Grade 1: 14 (38.9%), Grade 2: 3 (8.3%), and Grade 3: 8 (22.2%). The grade of artifacts differed across surgery types (P = 0.019). Grade 3 artifacts were higher in breast conserving cases whereas Grade 0 was more frequent in subcutaneous mastectomy cases. Three out of 69 (4.4%) cases who had follow-up mammography had artifacts due to iron oxide particle accumulation which presented as Grade 3 MRI artifact in all.

CONCLUSION

Accumulation of iron oxide particles after SLNB with paramagnetic tracers causes artifacts on follow-up MRI examinations in half of the cases but it is significantly low in mammograms. These artifacts may be confusing in the evaluation of the images. Radiologists must be aware of these tracers and their artifacts whereas patients should be questioned for the type of SLNB before a follow-up examination.

Correlation between ferromagnetic and isotopic tracers for sentinel lymph node detection in cutaneous melanoma: IMINEM study

BACKGROUND

The usefulness of sentinel lymph node biopsy (SLNB) in staging cutaneous melanoma has been proven. Therefore, different tracers have been used to identify the sentinel lymph nodes (SLNs). The use of isotopic tracers together with radioactivity detectors allowed a much more precise and direct approach to the SLNs. However, not all centres have access to a Nuclear Medicine department hindering sentinel lymph node detection (SLND) and consequently, other markers such as ferromagnetic tracers have been evaluated looking for the same advantages and effectiveness as isotopic tracers. Ferromagnetic tracers have proven their usefulness in other cancer entities such as breast, prostate and thyroid cancer. The objective was to assess the detection and concordance rates between isotopic and ferromagnetic techniques for SLNB in cutaneous melanoma.

METHOD

Isotopic SLNB technique and ferromagnetic tracer were compared for cutaneous melanoma in a non-inferiority multicentre prospective study carried out in six Spanish hospitals.

RESULTS

A total of 60 patients were recruited and 133 lymph nodes removed. The detection rate was slightly higher with ferromagnetic tracer in head-neck and trunk melanomas, and with isotopic tracer in limbs. The patients' and nodes' concordance rates between both techniques for ex vivo samples were 95% and 86% for head-neck and trunk tumours and 97% and 93% for limbs tumours, respectively. The concordance rates for involved nodes were 100% and 88.2% for patients and nodes, respectively.

CONCLUSION

The intraoperative detection and biopsy of SLN in cutaneous melanoma using a ferromagnetic was a reliable alternative method to the isotopic technique in cutaneous melanomas.

Moving Beyond the Pillars of Cancer Treatment: Perspectives From Nanotechnology

Nanotechnology has made a significant impact on basic and clinical cancer research over the past two decades. Owing to multidisciplinary advances, cancer nanotechnology aims to address the problems in current cancer treatment paradigms, with the ultimate goal to improve treatment efficacy, increase patient survival, and decrease toxic side-effects. The potential for use of nanomedicine in cancer targeting and therapy has grown, and is now used to advance the four traditional pillars of cancer treatment: surgery, chemotherapy, radiation therapy and the newest pillar, immunotherapy. In this review we provide an overview of notable advances of nanomedicine in improving drug delivery, radiation therapy and immunotherapy. Potential barriers in the translation of nanomedicine from bench to bedside as well as strategies to overcome these barriers are also discussed. Promising preclinical findings highlight the translational and clinical potential of integrating nanotechnology approaches into cancer care.

Superparamagnetic iron oxide: a novel tracer for sentinel lymph node detection in vulvar cancer

OBJECTIVES

Superparamagnetic techniques for sentinel lymph node (SLNs) biopsy in breast cancer is well recognized but remains novel in the literature in relation to early stage vulvar cancer. The aim of this study was to compare and validate SLN detection using a superparamagnetic iron oxide tracer and a magnetometer probe compared with the standard procedure with a radioisotope (⁹⁹Tc-technetium 99) and a gamma probe, in patients with vulvar cancer.

METHODS

Patients were included in the study with squamous vulvar tumors less than 4 cm in diameter and without suspicious groin lymph nodes on preoperative magnetic resonance imaging. Patients must have previously qualified for SLN biopsy with a radiotracer as the standard of care. The primary endpoint was the proportion of successful SLN detection with superparamagnetic iron oxide tracer versus ⁹⁹Tc. The secondary endpoints were average number of SLNs retrieved per patient, proportion of SLNs detected (nodal detection rate), and proportion of pathologically positive results (malignancy rate) per patient and per node comparing both SLN detection methods.

RESULTS

A total of 20 patients were included in the study. SLNs were found in all patients with both methods, resulting in similar average distributions (3.1/3.2 SLN per patient). The SLN detection rate per patient was 100% with both techniques. Nodal detection sensitivity was 98.5% for the superparamagnetic technique and 93.8% for the radiotracer. Percentage of metastatic lymph nodes detected was 100% with both tracers. The rate of lymph node positivity was 21.5% (14 lymph nodes with metastases) and for patients 45% (9 patients with nodal metastases). Additionally, SLN tainted brown due to superparamagnetic iron oxide nanoparticles in 19 of 20 patients.

CONCLUSIONS

The use of superparamagnetic iron oxide tracer in patients with vulvar cancer seems reliable and not inferior to the standard approach with radiotracer.

A randomized study comparing different doses of superparamagnetic iron oxide tracer for sentinel lymph node biopsy in breast cancer: The SUNRISE study

INTRODUCTION

The non-radioactive method that uses the magnetic tracer (SPIO/Sienna) has shown to be a feasible technique for the SLN detection in breast cancer patients. The aim of this study is to assess the efficacy of different doses of a new magnetic tracer Sienna XP (Magtrace) compared to Tc-99 m and to evaluate its non-inferiority.

METHODS

Patients diagnosed with early-stage breast cancer cT1-3 N0, from October 2016 to August 2018 were eligible and consecutively randomized to three different doses of new SPIO used: group 1 (1 mL), group 2 (1.5 mL) and group 3 (2 mL).

RESULTS

A total of 135 patients were included in the study, 45 in each group. Detection of SLNs with the three doses of Sienna XP (1 mL, 1.5 mL and 2 mL) showed non-inferior rates compared to the conventional technique with radiotracer (p = 0.654). Concordance by patients with SLN positive was 100% for all groups. 83 (70.3%) patients reported skin staining at one month postoperatively, significantly lower in group 1 (p = 0.042). At 6 months follow up, group 1 remains with significantly lower skin discoloration (p = 0,01). In multivariate analysis, dose of 2 mL showed statistically significant for the skin staining. The majority of patients (70%) felt that skin discoloration does not represent a problem.

CONCLUSION

The use of the Sienna XP magnetic tracer at 1 mL is not inferior to higher doses of magnetic tracer neither is inferior to radiotracer. 1 mL of magnetic tracer resulted in significantly less skin discoloration compared to higher doses.

Moving a neodymium magnet promotes the migration of a magnetic tracer and increases the monitoring counts on the skin surface of sentinel lymph nodes in breast cancer

Background

We suspected that moving a small neodymium magnet would promote migration of the magnetic tracer to the sentinel lymph node (SLN). Higher monitoring counts on the skin surface before making an incision help us detect SLNs easily and successfully. The present study evaluated the enhancement of the monitoring count on the skin surface in SLN detection based on the magnet movement in a sentinel lymph node biopsy (SNB) using superparamagnetic iron oxide (SPIO) nanoparticles.

Methods

After induction of general anesthesia, superparamagnetic iron oxide nanoparticles were injected sub-dermally into the subareolar area or peritumorally. The neodymium magnet was moved over the skin from the injection site to the axilla to promote migration of the magnetic tracer without massage. A total of 62 patients were enrolled from February 2018 to November 2018: 13 cases were subjected to magnet movement 20 times (Group A), 8 were subjected to 1-min magnet movement (Group B), 26 were given a short (about 5 min) interval from injection to 1-min magnet movement (Group C), and 15 were given a long (about 25 min) interval before 1-min magnet movement using the magnetometer’s head (Group D). In all cases, an SNB was conducted using both the radioisotope (RI) and SPIO methods. The monitoring counts on the skin surface were measured by a handheld magnetometer and compared among the four groups. Changes in the monitoring count by the interval and magnet movement were evaluated.

Results

The identification rates of the SPIO and RI methods were 100 and 95.2%, respectively. The mean monitoring counts of Group A, B, C, and D were 2.39 μT, 2.73 μT, 3.15 μT, and 3.92 μT, respectively (p < 0.0001; Kruskal-Wallis test). The monitoring counts were higher with longer magnet movement and with the insertion of an interval. Although there were no relationships between the monitoring count on the skin surface and clinicopathologic factors, magnet movement strongly influenced the monitoring count on the skin surface.

Conclusion

Moving a small neodymium magnet is effective for promoting migration of a magnetic tracer and increasing monitoring counts on the skin surface.

Trial registration

UMIN, UMIN000029475. Registered 9 October 2017

Superparamagnetic iron oxide as a tracer for sentinel lymph node detection in uterine cancer: a pilot study

Sentinel lymph node (SLN) mapping using dye or radioisotopes has been performed in patients with uterine cancer. Superparamagnetic iron oxide (SPIO) can be handled safely and is taken up by lymph nodes (LNs); however, its efficacy in detecting SLNs in uterine cancer remains unknown. This pilot study evaluated the use of SPIO as a tracer for SLN detection in patients with uterine cancer. SPIO was injected into the uterine cervixes of 15 patients with uterine cancer scheduled for pelvic LN dissection. Magnetic resonance imaging (MRI) was performed preoperatively. Five patients also underwent radioisotope injection and single-photon emission computed tomography/computed tomography. Dissected LNs were stained with iron and examined pathologically. Of the radioisotope-positive LNs, 92% were also SPIO/MRI-positive. SPIO/MRI and iron staining were positively correlated. SLNs were identified by iron staining in 93% of cases. Iron staining was strongly positive in two of the five areas of LN metastasis; these were considered SLNs. Staining was negative or very weak in the other three areas and lymph flow disturbance was considered. SPIO and radioisotopes are taken up similarly by SLNs. SPIO/MRI and iron staining may thus be useful for detection of SLNs and diagnosis of LN metastasis in patients with uterine cancer.

Accuracy of Sentinel Lymph Node Biopsy in Breast Cancer: Pitfalls in the Application of Single Tracers

Background

Radioisotopes and blue dyes are used as dual tracers in the current gold standard procedure of sentinel lymph node (SLN) biopsy (SLNB) performed for breast cancer. However, the blue dye or the radioisotope as a single tracer is also being applied in some institutes. We aimed to explore the risk factors for the miss-detection of SLNs with the radioisotope and the blue dye and to describe the distribution of SLNs missed by each tracer.

Patients and Methods

Patients undergoing SLNB with radioisotope and blue dye as dual mapping agents were enrolled between August 2010 and August 2018. Radioactivity count, blue dye staining status, and size and location of each SLN were prospectively documented.

Results

In total, 2382 SLNs from 1010 patients were included for statistical analyses. The sentinel node identification rate was 100% for dual tracers, 99.4% for radioisotope, and 89.1% for blue dye. SLN identification using the blue dye was more likely to fail in patients undergoing breast-conserving surgery (p < 0.001) and mastectomy with reconstruction (p = 0.005). Furthermore, miss-detection was significantly more frequent in smaller and uninvolved nodes. Among all SLNs, 8.2% were located in level II and one was in level III. Notably, single tracer of blue dye tended to fail in the detection of lymph nodes in higher levels (p < 0.001).

Conclusion

This study explored the association between features and the incidence of the failure to detect SLNs using radioisotope and blue dye. The locations of the miss-detected SLNs are demonstrated to provide a reference for SLNBs conducted using blue dye or radioisotope as a single tracer.

Development of Magnetic Probe for Sentinel Lymph Node Detection in Laparoscopic Navigation for Gastric Cancer Patients

New laparoscopic sentinel lymph node navigation using a dedicated magnetic probe and magnetic nanoparticle tracer for gastric cancer patients allows minimally invasive surgeries. By identifying the sentinel lymph nodes containing magnetic nanoparticles, patients can avoid excessive lymph node extraction without nuclear facilities and radiation exposure. This paper describes the development of the laparoscopic magnetic probe, ACDC-probe, for laparoscopic sentinel lymph node identification utilizing the nonlinear response of the magnetic nanoparticles magnetized by an alternating magnetic field with a static magnetic field. For highly sensitive detection, the ratio of static to alternating magnetic fields was optimized to approximately 5. The longitudinal detection length was approximately 10 mm for 140 μg of iron, and the detectable amount of iron was approximately 280 ng at a distance of 1 mm. To demonstrate the feasibility of laparoscopic detection using the ACDC-probe and magnetic tracers, an experiment was performed on a wild swine. The gastric sentinel lymph node was clearly identified during laparoscopic navigation. These results suggest that the newly developed ACDC-probe is useful for laparoscopic sentinel lymph node detection and this magnetic technique appears to be a promising method for future sentinel lymph node navigation of gastric cancer patients.

Advanced Nanotechnology Leading the Way to Multimodal Imaging-Guided Precision Surgical Therapy

Surgical resection is the primary and most effective treatment for most patients with solid tumors. However, patients suffer from postoperative recurrence and metastasis. In the past years, emerging nanotechnology has led the way to minimally invasive, precision and intelligent oncological surgery after the rapid development of minimally invasive surgical technology. Advanced nanotechnology in the construction of nanomaterials (NMs) for precision imaging-guided surgery (IGS) as well as surgery-assisted synergistic therapy is summarized, thereby unlocking the advantages of nanotechnology in multimodal IGS-assisted precision synergistic cancer therapy. First, mechanisms and principles of NMs to surgical targets are briefly introduced. Multimodal imaging based on molecular imaging technologies provides a practical method to achieve intraoperative visualization with high resolution and deep tissue penetration. Moreover, multifunctional NMs synergize surgery with adjuvant therapy (e.g., chemotherapy, immunotherapy, phototherapy) to eliminate residual lesions. Finally, key issues in the development of ideal theranostic NMs associated with surgical applications and challenges of clinical transformation are discussed to push forward further development of NMs for multimodal IGS-assisted precision synergistic cancer therapy.

Nanomedicines - Tiny particles and big challenges

After decades of research, nanotechnology has been used in a broad array of biomedical products including medical devices, drug products, drug substances, and pharmaceutical-grade excipients. But like many great achievements in science, there is a fine balance between the risks and opportunities of this new technology. Some materials and surface structures in the nanosize range can exert unexpected toxicities and merit a more detailed safety assessment. Regulatory agencies such as the United States Food and Drug Administration or the European Medicines Agency have started dealing with the potential risks posed by nanomaterials. Considering that a thorough characterization is one of the key aspects of controlling such risks this review presents the regulatory background of nanosafety assessment and provides some practical advice on how to characterize nanomaterials and drug formulations. Further, the challenges of how to maintain and monitor pharmaceutical quality through a highly complex production processes will be discussed.