Nuclear medicine contribution to precision surgery in breast cancer

Nuclear medicine has significantly contributed to precision surgery in breast cancer in the past decades. Radioguided surgery (RGS) has enabled sentinel node (SN) biopsy in assessing regional nodal involvement modifying the management of patients with early breast cancer. For the axilla the SN procedure has resulted in fewer complications and better quality of life when compared with axillary lymph node dissection. Originally, SN biopsy principally concerned cT 1-2 tumours without evidence of axillary lymph node metastases. However, in last years SN biopsy is also being offered to patients with large or multifocal tumours, ductal carcinoma in situ, ipsilateral breast cancer relapse, and to patients receiving neoadjuvant systemic treatment (NST) for breast sparing surgery. Parallel to this evolution various scientific associations are trying to homogenise issues such as radiotracer choice, breast injection site, preoperative imaging standardisation and SN biopsy timing in relation to NST as well as management of non-axillary SN metastasis (e.g. internal mammary chain). Additionally, RGS is currently used to accomplish primary breast tumour excision either by intralesional radiocolloid injection or by radioactive iodine seed implantation which is also employed to target metastatic axillary lymph nodes. This latter procedure contributes to manage the node-positive axilla in combination with 18F-FDG PET/CT in an effort to tailor systemic and loco regional treatment.

The applicability of Magseed® for targeted axillary dissection in breast cancer patients treated with neoadjuvant chemotherapy

Background

Targeted axillary dissection (TAD), the combination of sentinel lymph node biopsy (SLNB) and targeted lymph node biopsy (TLNB), can reduce the false negative rates of sentinel node biopsy alone dramatically in breast cancer patients, who received neoadjuvant chemotherapy (NAC). However methods for TAD are still under investigation.

Methods

Magseed®, a non-radioactive magnetic marker was used to mark the biopsied positive TLN after NAC. The SLNB with the standard technetium-based method and the selective TLNB with Magseed® localization were performed in 40 patients. The TLNs were identified with the Sentimag® probe and excised in all patients. Specimen x-ray was performed to confirm the Magseed® within the prior to NAC biopsied and clipped lymph node.

Results

The TLN identification rate was 100% (40/40), the SLN identification rate was 82.5% (33/40), the concordance rate between the TLN and the SLN was 65% (26/40). Complications according Magseed® deployment or identification could not be observed.

Conclusion

Magseed® is a reliable and feasible marker for the identification of TLNs after NAC.

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TLNB is an accurate method for the identification of marked lymph nodes after NAC.

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Selective excision of TLNs is feasible.

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Magseed® allows a non-radioactive, wireless marking of TLNs.