Targeted axillary dissection (TAD) with a radioactive seed is a new and promising technique to evaluate the axillary status in post-neoadjuvant chemotherapy (NACT) node-positive breast cancer patients. This study aims to evaluate the feasibility of TAD with a radioactive seed in a Canadian setting.

We conducted a retrospective observational study of a prospectively gathered database of patients having undergone TAD with a radioactive seed implanted in a proven metastatic axillary node, between 2015 and 2017. An iodine-125 radioactive seed was implanted under ultrasound guidance by trained radiologists. Patients then underwent standard sentinel lymph node biopsy (SLNB) using technicium-99 and blue dye, as well as selective removal of the node containing the radioactive seed. Data was gathered from electronic medical records and chart review.

Nine patients with a median age of 54 underwent TAD for unilateral breast cancer post-NACT between 2015 and 2017, three of which were “triple negative”. A median of 3 lymph nodes were removed, including that which contained the radioactive seed. Postoperative pathological evaluation showed 4 patients with positive nodes and 5 pathologic complete responses in the axilla. In all patients, the seed had been accurately positioned in a positive node (no false negatives). The seed also located a positive retropectoral node that would otherwise have been missed using standard dual tracer SLNB. No complications due to the use of the radioactive seed were encountered. All implanted seeds were identified and retrieved within the pathology specimen.

In our experience, TAD with a radioactive seed combined to dual tracer SNLB is an accurate and safe method of evaluating the axillary lymph node status in post-NACT node positive breast cancer patients. Further studies with larger cohorts are warranted to ensure continued feasibility and reproducibility of our positive results.

Radioactive seed and targeted axillary dissection: a feasibility study