Abstract P1-16-09: Magnetic sentinel node and occult lesion localization in breast cancer: Initial results of the MagSNOLL trial

Trial registration:

ISRCTN: 68689512

MREC No: 13/LO/0636

UKCRN ID: 14979

INTRODUCTION:

One-third of breast cancers diagnosed are non-palpable. These breast cancers require localization-guided surgery and axillary staging using sentinel lymph node biopsy (SLNB). We present our experience of the first 20 patients undergoing a novel technique of magnetic-guided lesion localization and concurrent SLNB, avoiding the need for wire-guided localization and radioisotopes.

MATERIALS AND METHODS:

Co-localization of the primary tumour and sentinel lymph nodes (SLNs) using a novel magnetic technique was initially undertaken on a protocol-driven predefined minimum of 10 patients with palpable breast cancers to assess the feasibility of the magnetic tracer to safely localize at the point of injection and concurrently drain to the lymphatics. In order to confirm proof of principle, the subsequent 20 patients with non-palpable breast cancers were analysed. An ultrasound-guided intra-tumoral injection of magnetic tracer was performed (0.5 mL Sienna+, Endomagnetics Ltd, UK). Once successful lesion localization was confirmed (peak magnetometer counts retained at the site of injection), the technique was undertaken in patients with non-palpable breast cancers awaiting wide local excision and SLNB. All patients underwent SLNB with the magnetic and combined technique (radioisotope and Patent Blue Dye).

RESULTS:

A total of 33 patients were recruited and 1 patient excluded due to breach of the trial protocol. This left a remainder of 32 patients for consideration, of which 12 patients (1 bilateral) possessed palpable breast cancer and 20 patients non-palpable breast cancer. Peak magnetometer counts were retained at the site of injection in all palpable (n=13) and non-palpable (n=20) breast cancers. Re-excisions (second operations) for involved margins were performed in 2 patients with non-palpable breast cancers (10%). The mean volume of excised specimens was 49 cm3 (SD 30.6). The SLN identification rate for the magnetic technique alone was 84% (28/33) overall and 85% (17/20) for non-palpable lesions. For the combined technique (radioisotope and blue dye) the SLN identification rate was 97% (32/33) overall and 100% (20/20) for non-palpable lesions. When the magnetic technique is combined with blue dye, the SLN identification rate overall was 97% (32/33) and for non-palpable breast cancers was 95% (19/20). The mean number of sentinel nodes excised was 1.75 versus 2.05 for the magnetic and combined techniques respectively.

CONCLUSION: Magnetic lesion localization and concurrent SLNB is a feasible technique. Further optimisation and validation of this technique, in a larger trial, is required.

Citation Format: Muneer Ahmed, Ashutosh Kothari, Hisham Hamed, Sumit Goyal, Tibor Kovacs, Anand David Purushotham, Bauke Anninga, Phillippa Young, Julie Scudder, Sarah McWililliams, Sarah Pinder, Quentin Pankhurst, Ian Monnypenny, Michael Douek. Magnetic sentinel node and occult lesion localization in breast cancer: Initial results of the MagSNOLL trial [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-16-09.

High-intensity focused ultrasound for the treatment of fibroadenomata (HIFU-F) study

Background

Breast fibroadenomata (FAD) are the most common benign lesions in women. For palpable lesions, there are currently three standard treatment options: reassurance (with or without follow-up), vacuum-assisted mammotomy (VAM) or surgical excision. High-intensity focused ultrasound (HIFU) ablation has been used in the treatment of FAD. The drawback of HIFU is its prolonged treatment duration. The aim of this trial is to evaluate circumferential HIFU treatment for the effective ablation of FAD with a reduced treatment time.

Methods/design

Fifty patients (age ≥18 years) will be recruited with symptomatic FAD, visible on ultrasound (US, grade U2 benign). In patients ≥25 years, cytology or histology will be performed to confirm the diagnosis of a FAD. These patients will receive HIFU treatment using the US-guided Echopulse device (Theraclion Ltd., Malakoff, France) under local anaesthesia. An additional 50 patients will be recruited and contacted 6 months after discharge from the breast clinic. These patients will be offered an US scan to determine the change in size of their FAD. This natural change in size will be compared to the decrease in size after HIFU treatment. Secondary outcome measures include post-treatment complications, patient recorded outcome measures, mean treatment time and cost analysis.

Trial registration

Current Controlled Trials: ISRCTN76622747.

Intraoperative radiotherapy in early breast cancer

BACKGROUND

Intraoperative radiotherapy (IORT) constitutes a paradigm shift from the conventional 3-5 weeks of whole-breast external beam radiotherapy (EBRT). IORT enables delivery of radiation at the time of excision of the breast tumour, targeting the area at highest risk of recurrence, while minimizing excessive radiation exposure to healthy breast tissue. The rationale for IORT is based on the observation that over 90 per cent of local recurrences after breast-conserving surgery occur at or near the original operation site.

METHODS

This article reviews trials of IORT delivered with different techniques and devices.

RESULTS

IORT is a very attractive option for delivering radiotherapy, reducing the traditional fractionated treatment to a single fraction administered at the time of surgery. IORT has been shown to be associated with reduced toxicity and has several potential benefits over EBRT. Only two randomized clinical trials have been published to date. The TARGIT-A and ELIOT trials have demonstrated that IORT is associated with a low rate of local recurrence, although higher than that after EBRT (TARGIT-A: 3·3 versus 1·3 per cent respectively, P = 0·042; ELIOT: 4·4 versus 0·4 per cent, P < 0·001). However, the local recurrence rate for IORT fell within the predefined 2·5 per cent non-inferiority margin in TARGIT-A, and the 7·5 per cent equivalence margin in ELIOT.

CONCLUSION

Longer follow-up data from existing trials, optimization of patient criteria and cost-effectiveness analyses are needed. Based on the current evidence, IORT can be offered as an alternative to EBRT to selected patients within agreed protocols, and outcomes should be monitored within national registries.

Is IORT ready for roll-out?

Two large randomised controlled trials of intraoperative radiotherapy (IORT) in breast-conserving surgery (TARGIT-A and ELIOT) have been published 14 years after their launch. Neither the TARGIT-A trial nor the ELIOT trial results have changed the current clinical practice for the use of IORT. The in-breast local recurrence rate (LRR) after IORT met the pre-specified non-inferiority margins in both trials and was 3.3% in TARGIT-A and 4.4% in the ELIOT trial. In both trials, the pre-specified estimates for local recurrence (LR) with external beam radiation therapy (EBRT) significantly overestimated actual LRR. In the TARGIT-A trial, LR with EBRT was estimated at the outset to be 6%, and in the ELIOT trial, it was estimated to be 3%. Surprisingly, LRR in the EBRT groups has been found to be significantly lower, 1.3% in the EBRT arm of the TARGIT-A and 0.4% in the EBRT arm of the ELIOT trial, respectively. Median follow-up was 2.4 years for the TARGIT-A trial and 5.8 years for the ELIOT trial. However, the initial cohort of patients in the TARGIT-A trial (reported in 2010) now have a median follow-up of 3.8 years and data on LR were available at 5 years follow-up on 35% of patients (18% who received IORT). Although further follow-up will increase confidence with the data, it will also further delay clinical implementation. By carefully weighing the risks and benefits of a single-fraction radiation treatment with patients, IORT should be offered within agreed and strict protocols. Patients deemed at low risk of LR or those deemed suitable for partial breast irradiation, according to the GEC-ESTRO and ASTRO recommendations, could be considered as candidates for IORT. These guidelines apply to all partial breast irradiation techniques, and more specific guidelines for IORT would assist clinicians.

Optimising magnetic sentinel lymph node biopsy in an in vivo porcine model

The magnetic technique for sentinel lymph node biopsy (SLNB) has been evaluated in several clinical trials. An in vivo porcine model was developed to optimise the magnetic technique by evaluating the effect of differing volume, concentration and time of injection of magnetic tracer. A total of 60 sentinel node procedures were undertaken. There was a significant correlation between magnetometer counts and iron content of excised sentinel lymph nodes (SLNs) (r=0.82; P<0.001). Total number of SLNs increased with increasing volumes of magnetic tracer (P<0.001). Transcutaneous magnetometer counts increased with increasing time from injection of magnetic tracer (P<0.0001), plateauing within 60min. Increasing concentration resulted in higher iron content of SLNs (P=0.006). Increasing magnetic tracer volume and injecting prior to surgery improve transcutaneous 'hotspot' identification but very high volumes, increase the number of nodes excised.

FROM THE CLINICAL EDITOR

Sentinel lymph node biopsy (SLNB) is the standard of care for axillary staging of breast cancer patients. Although the current gold standard technique is the combined injection of technetium-labelled nanocolloid and blue dye into the breast, the magnetic technique, using superparamagnetic carboxydextran-coated iron oxide (SPIO), has also been demonstrated as a feasible alternative. In this article, the authors set up to study factors in order to optimize the magnetic tracers.

Comparison of three magnetic nanoparticle tracers for sentinel lymph node biopsy in an in vivo porcine model

Introduction

Breast cancer staging with sentinel lymph node biopsy relies on the use of radioisotopes, which limits the availability of the procedure worldwide. The use of a magnetic nanoparticle tracer and a handheld magnetometer provides a radiation-free alternative, which was recently evaluated in two clinical trials. The hydrodynamic particle size of the used magnetic tracer differs substantially from the radioisotope tracer and could therefore benefit from optimization. The aim of this study was to assess the performance of three different-sized magnetic nanoparticle tracers for sentinel lymph node biopsy within an in vivo porcine model.

Materials and methods

Sentinel lymph node biopsy was performed within a validated porcine model using three magnetic nanoparticle tracers, approved for use in humans (ferumoxytol, with hydrodynamic diameter d_H =32 nm; Sienna+^®, d_H =59 nm; and ferumoxide, d_H =111 nm), and a handheld magnetometer. Magnetometer counts (transcutaneous and ex vivo), iron quantification (vibrating sample magnetometry), and histopathological assessments were performed on all ex vivo nodes.

Results

Transcutaneous “hotspots” were present in 12/12 cases within 30 minutes of injection for the 59 nm tracer, compared to 7/12 for the 32 nm tracer and 8/12 for the 111 nm tracer, at the same time point. Ex vivo magnetometer counts were significantly greater for the 59 nm tracer than for the other tracers. Significantly more nodes per basin were excised for the 32 nm tracer compared to other tracers, indicating poor retention of the 32 nm tracer. Using the 59 nm tracer resulted in a significantly higher iron accumulation compared to the 32 nm tracer.

Conclusion

The 59 nm tracer demonstrated rapid lymphatic uptake, retention in the first nodes reached, and accumulation in high concentration, making it the most suitable tracer for intraoperative sentinel lymph node localization.

Magnetic guidance for cancer surgery

Attractive

Meta-analysis of superficial versus deep injection of radioactive tracer and blue dye for lymphatic mapping and detection of sentinel lymph nodes in breast cancer

BACKGROUND

Sentinel lymph node biopsy (SLNB) is the standard of care for axillary staging in early breast cancer. Currently, no consensus exists on the optimal site of injection of the radioactive tracer or blue dye.

METHODS

A systematic review and meta-analysis of studies comparing superficial and deep injections of radioactive tracer or blue dye for lymphatic mapping and SLNB was performed. The axillary and extra-axillary sentinel lymph node (SLN) identification rates obtained by lymphoscintigraphy and intraoperative SLNB were evaluated. Pooled odds ratios (ORs) and 95 per cent c.i. were estimated using fixed-effect analyses, or random-effects analyses if there was statistically significant heterogeneity (P < 0·050).

RESULTS

Thirteen studies were included in the meta-analysis. There was no significant difference between superficial and deep injections of radioactive tracer for axillary SLN identification on lymphoscintigraphy (OR 1·59, 95 per cent c.i. 0·79 to 3·17), during surgery (OR 1·27, 0·60 to 2·68) and for SLN identification using blue dye (OR 1·40, 0·83 to 2·35). The rate of extra-axillary SLN identification was significantly greater when deep rather than superficial injection was used (OR 3·00, 1·92 to 4·67). The discordance rate between superficial and deep injections ranged from 4 to 73 per cent for axillary and from 0 to 61 per cent for internal mammary node mapping.

CONCLUSION

Both superficial and deep injections of radioactive tracer and blue dye are effective for axillary SLN identification. Clinical consequences of discordance rates between the two injection techniques are unclear. Deep injections are associated with significantly greater extra-axillary SLN identification; however, this may not have a significant impact on clinical management.

Novel techniques for sentinel lymph node biopsy in breast cancer: a systematic review

The existing standard for axillary lymph node staging in breast cancer patients with a clinically and radiologically normal axilla is sentinel lymph node biopsy with a radioisotope and blue dye (dual technique). The dependence on radioisotopes means that uptake of the procedure is limited to only about 60% of eligible patients in developed countries and is negligible elsewhere. We did a systematic review to assess three techniques for sentinel lymph node biopsy that are not radioisotope dependent or that refine the existing method: indocyanine green fluorescence, contrast-enhanced ultrasound using microbubbles, and superparamagnetic iron oxide nanoparticles. Our systematic review suggested that these new methods for sentinel lymph node biopsy have clinical potential but give high levels of false-negative results. We could not identify any technique that challenged the existing standard procedure. Further assessment of these techniques against the standard dual technique in randomised trials is needed.

The management of screen-detected breast cancer

The increased use of mammography and introduction of breast screening programmes have resulted in a rise in clinically-occult breast cancer, with one-third of all breast carcinomata diagnosed being non-palpable. These types of cancer have a unique natural history and biology compared to symptomatic breast cancer and this needs to be taken into account when considering surgery and adjuvant treatment. The majority of studies demonstrating efficacy of adjuvant treatments are largely based on patients with symptomatic breast cancer. The current evidence for the role of surgery and adjuvant therapy for screen-detected breast cancer was reviewed in light of their improved prognosis, compared to symptomatic breast cancer.

Sentinel node biopsy using a magnetic tracer versus standard technique: the SentiMAG Multicentre Trial

BACKGROUND

The SentiMAG Multicentre Trial evaluated a new magnetic technique for sentinel lymph node biopsy (SLNB) against the standard (radioisotope and blue dye or radioisotope alone). The magnetic technique does not use radiation and provides both a color change (brown dye) and a handheld probe for node localization. The primary end point of this trial was defined as the proportion of sentinel nodes detected with each technique (identification rate).

METHODS

A total of 160 women with breast cancer scheduled for SLNB, who were clinically and radiologically node negative, were recruited from seven centers in the United Kingdom and The Netherlands. SLNB was undertaken after administration of both the magnetic and standard tracers (radioisotope with or without blue dye).

RESULTS

A total of 170 SLNB procedures were undertaken on 161 patients, and 1 patient was excluded, leaving 160 patients for further analysis. The identification rate was 95.0 % (152 of 160) with the standard technique and 94.4 % (151 of 160) with the magnetic technique (0.6 % difference; 95 % upper confidence limit 4.4 %; 6.9 % discordance). Of the 22 % (35 of 160) of patients with lymph node involvement, 16 % (25 of 160) had at least 1 macrometastasis, and 6 % (10 of 160) had at least a micrometastasis. Another 2.5 % (4 of 160) had isolated tumor cells. Of 404 lymph nodes removed, 297 (74 %) were true sentinel nodes. The lymph node retrieval rate was 2.5 nodes per patient overall, 1.9 nodes per patient with the standard technique, and 2.0 nodes per patient with the magnetic technique.

CONCLUSIONS

The magnetic technique is a feasible technique for SLNB, with an identification rate that is not inferior to the standard technique.