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

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.

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.

Image-Guided Localization Techniques for Metastatic Axillary Lymph Nodes in Breast Cancer; What Radiologists Should Know

Targeted axillary dissection (TAD) is an axillary staging technique after NACT that involves the removal of biopsy-proven metastatic lymph nodes in addition to sentinel lymph node biopsy (SLNB). This technique avoids the morbidity of traditional axillary lymph node dissection and has shown a lower false-negative rate than SLNB alone. Therefore, marking positive axillary lymph nodes before NACT is critical in order to locate and remove them in the subsequent surgery. Current localization methods include clip placement with intraoperative ultrasound, carbon-suspension liquids, localization wires, radioactive tracer-based localizers, magnetic seeds, radar reflectors, and radiofrequency identification devices. The aim of this paper is to illustrate the management of axillary lymph nodes based on current guidelines and explain the features of axillary lymph node markers, with relative advantages and disadvantages.

Survival After Sentinel Lymph Node Biopsy Compared with Axillary Lymph Node Dissection for Female Patients with T3-4c Breast Cancer

BACKGROUND

For patients with cN0 and T1-2 breast cancer, sentinel lymph node biopsy (SLNB) can provide survival results equivalent to axillary lymph node dissection (ALND). However, whether it can be performed on T3-4c patients is still controversial.

MATERIALS AND METHODS

Female patients diagnosed with cN0, T3-4c, and M0 breast cancer from 2004 to 2019 were identified using the surveillance, epidemiology and end results (SEER) database and divided into 2 groups, the SLNB group (1-5 regional lymph nodes examined) and the ALND group (≥10 regional lymph nodes examined). Finally, only those with pN0 disease were included in the SLNB group. The baseline differences in clinicopathological characteristics between groups were eliminated by propensity score matching (PSM). We also conducted subgroup analyses according to age, overall TNM stage, breast cancer subtypes, surgical approaches, radiation therapy, and chemotherapy. The primary endpoint was survival.

RESULTS

With a mean follow-up of 75 months, a total of 186 deaths were reported among 864 patients. The overall survival (OS) and breast cancer-specific survival (BCSS) in the SLNB group were 78.2% and 87.5%, respectively, and that in the ALND group were 78.7% and 87.3%, respectively. The unadjusted hazard ratio (HR) for OS and BCSS in the SLNB group (vs. the ALND group) was 0.922 (95% CI, 0.691-1.230, P = .580) and 0.874 (95% CI, 0.600-1.273, P = .481), respectively. Besides, the OS and BCSS between the 2 groups were also similar in all subgroup analyses.

CONCLUSIONS

SLNB may be performed on female patients with cN0, T3-4c, and M0 breast cancer.