Radioguided surgery with iodine-125 seeds in breast cancer patients treated with neoadjuvant chemotherapy

To evaluate the use of radioactive iodine-125 seed (RIS) in breast and/or axillary surgery, in patients with breast cancer treated with neoadjuvant chemotherapy (NAC).

Prospective study between January 2016 and June 2020. 80 women T1-3,N0-2,M0: 30 RIS marking the breast tumor, 36 both the tumor and the biopsied positive axillary node, and 14 only the axilla. Age: 54.7±11.4 years. Tumor size: 34.1±14.6mm. Histological type: invasive ductal carcinoma 90.0%. Molecular subtypes: luminal-A 23.8%, luminal-B/HER2- 33.7%, luminal-B/HER2+ 18.8%, HER2+ 7.5%, basal-like 16,2%.

Of the 66 patients with RIS marking of the tumor (51 pre-NAC, 15 post-NAC), 92.1% had tumor-free surgical margins, with a specimen volume of 126.7±111.2 cm³. Of the 5 second local excisions, in 3 the resection margin was involved (1 mastectomy). Of the 50 patients N1 with RIS marking (MLN), 44 pre-NAC and 6 post-NAC, MLN was identified in 97.2%: negative 23, positive 26. In 45/50 patients, sentinel node biopsy (SNB) was performed and it was identified in 93.3%: negative 26, positive 16. In 1 case RIS was not placed correctly and SNB was not identified due to non-migration. In 61.9% of the patients, MLN was among the SNB identified in the surgery. In 5 patients with mismatched SNB and MLN, the pathological result of the SNB was negative and the MLN was positive. Axillary lymph node dissection was performed in 53.8% of the patients.

RIS allow to perform breast-conserving surgery and improve detection of residual axillary disease in patients treated with NAC.