327P - Defining ≥10% radioisotope-hot stained nodes as sentinel lymph nodes by “blue dye + radioisotope” dual-tracer method for sentinel lymph node biopsy leads to the overdetection and excessive excision

Background

Sentinel lymph node biopsy (SLNB) has been widely used to assess axillary staging. In clinical practice, it is crucial to define sentinel lymph node (SLN) and determine whether the detected nodes are SLNs during the process of SLNB. It is important to consider whether currently existing consensus on SLNB method which is dual-tracer technique may lead to the excessive and unnecessary removal of negative nodes. In addition, no uniform measurable and objective index has been established to define intra-operation palpable nodes, the excision of which may increase the random detection of SLN. The purpose of this study was to optimize the specific method of SLNB.

Methods

To propose an optimal cut-off value for “radioisotope+bule dye” dual-tracer method, the detailed information of (BC) patients who had no clinical node involvement and underwent SLNB from November 2010 to February 2021 was prospectively collected in the breast surgery department of West China Hospital. We analyzed the site and size, radioactivity, the status of blue dye and the pathological results of each node detected of each patients.

Results

A total of 4985 lymph nodes from 1595 BC patients were identified. Only 11.57% (577/4985) SLNs were defined as pathologically positive, resulting in 88.43% (4408/4985) negative nodes removed excessively. By gradually increasing the threshold of radioisotope count in comparison to the hottest SLN, we found that when elevating the cut-off value from 10% to approximately 60%, 17.3% of lymph nodes were spared removal, among which only 0.88% were missed positive SLNs. Raising the optimal cutoff value of radioisotopes to 60% and exempting palpable nodes at the same time could reduce the number of nodes detected by 30.81% with only 1.75% missed positive SLNs. Additionally, multivariate analysis in our study showed that larger tumor size and higher clinical N stage was significantly positively associated with SLN metastasis.

Conclusions

Raising the optimal cut-off value of radioisotope to 60% and exempting palpable nodes may be considered as a potential alternative method to avoid removing excessive negative nodes in SLNB.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Q. Lv.

Funding

West China Hospital, Sichuan University.

Disclosure

All authors have declared no conflicts of interest.