326P - Sentinel lymph node mapping in breast cancer: Evaluating the dual-tracer method with indocyanine green and radioisotope

Background

Indocyanine green (ICG) has the potential to improve sentinel lymph node (SLN) mapping. This current cohort study was designed to assess the value of ICG using a new ICG handheld system with radioisotope (RI) in patients with early breast cancer undergoing SLN biopsy.

Methods

A prospective self-controlled trial compared the detection efficacies of ICG and RI was conducted. Concordance (ICG and RI-positive cases divided by RI-positive cases) and reverse concordance (ICG and RI-positive cases divided by ICG-positive cases) were documented and adverse event were also assessed.

Results

Of 69 patients (median age 56.7 (range 33-85), median BMI 22.6 (range 17.0 – 44.5)) enrolled between 2019 and 2021, 71 SLN biopsies were performed. Sixty-one (85.9%) underwent upfront surgery, while ten (14.1%) were given neoadjuvant treatment. Thirty-four breast-conserving surgeries (BCS) (47.9%), 33 mastectomies (46.5%) and four cryotherapies (5.6%) were performed. No adverse event nor skin staining were reported. The SLN identification rate was 87.3% (62/71) for ICG and 95.8% (68/71) for RI (p=0.13). Dual tracer method resulted in 97.2% successful identification, significantly superior to ICG alone (p=0.04, OR 5.0, CI 1.0-24.1) and and was in line with the reported rate of 96.7% (94.3-99.1)¹ by blue dye and RI. Concordance and reverse concordance rates were 89.7% and 98.4%, respectively. A median of 2 lymph nodes was detected by both ICG (range 0 – 6) and IR (range 0 – 5) with no statistical difference (p=0.60). Of 10 cases with 13 metastatic nodes confirmed by histology, both ICG and RI achieved 100% concordance rates. Breast conserving treatments had a higher ICG failure rate compared to mastectomy (21.1% vs 3.0%, p=0.05, OR 8.5, CI 1.0-72.4). In addition, among three cases with prior surgery, two failed ICG SLN identification. Meanwhile, age, BMI, tumour location, multifocality, neoadjuvant treatment, and ICG volume showed no significant correlation with ICG detection rate.

Conclusions

The combined use of ICG and RI ensures adequate SLN identification without problems known with the use of blue dye, such as skin staining and anaphylaxis. A higher failure rate was noted in patients with breast-conserving treatments for ICG tracing.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.