318P - Evaluation of novel diagnostic kits using the semi-dry dot-blot method combined for detecting metastases in sentinel lymph nodes of patients with breast cancer: A multi-center prospective study

Background

The semi-dry dot-blot (SDB) method, a diagnostic procedure for detecting lymph node (LN) metastases using anti-cytokeratin (CK) antibody, is based on the theory that epithelial components such as CK are not found in normal LNs. Thus, metastases are diagnosed on basis of the presence of CK in lavage fluid of sectioned LNs. We prospectively evaluated novel SDB kits that use a newly developed anti-CK19 antibody and an automatic reader for diagnosing sentinel LN metastases in patients with breast cancer as a multi-center study.

Methods

We obtained 924 sentinel LNs dissected between January 2021 and December 2021 at six institutes in Japan. We excluded patients with neoadjuvant chemotherapy and neoadjuvant endocrine therapy. These LNs were sliced at 2-mm intervals and washed with PBS. Cells suspended in the lavage fluid of sliced LNs were centrifuged and lysed to extract protein. The extracted protein was applied to the SDB kit to diagnose LN metastasis using an automatic reader that evaluates absorbance. Washed LNs were blindly examined using intraoperative and permanent histological examination. Diagnoses based on SDB kit were compared with diagnoses made by permanent histological examination of the LNs. Primary endpoints were sensitivity, specificity, and overall agreement of the SDB kit for distinguishing macrometastases from non-macrometastases.

Results

Ninety-four of the 924 LNs were assessed as macrometastases, 40 as micrometastases and 790 as negative by histological examination. With a borderline CK19 absorbance of 11.9 milli-absorbance for detecting macrometastases with 0.989 Area Under the Curve, the sensitivity, specificity, and overall agreement of the SDB kit were 94.7%, 98.3%, and 97.9%, respectively. Furthermore, the kits and the automatic reader yielded diagnoses in approximately 20 min at a cost of less than 30 EUR for the SDB kit and less than 3,000 EUR for the automatic reader.

Conclusions

The kits with an automatic reader used in our study were accurate, quick, and cost-effective in diagnosing LN metastases without loss of LN tissue, and were especially useful for detecting distinguish macrometastases.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Japan Agency for Medical Research and Development.

Disclosure

All authors have declared no conflicts of interest.