Abstract PS1-39: Evaluation of novel diagnostic kits using the semi-dry dot-blot method combined with an automatic reader for detecting metastases in lymph nodes of patients with breast cancer : A single-center prospective study
Authors: Otsubo Ryota , Yano Hiroshi , Matsumoto Megumi , Tanaka Aya , Fukushima Ayako , Kuba Sayaka , Morita Michi , Uno Naoki , Yoon Han-Seung , Yanagihara Katsunori , Eguchi Susumu , Nagayasu Takeshi 
Published: February 2021

Abstract
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 LN metastases in patients with breast cancer. Methods: We obtained 117 LNs dissected from 58 patients with breast cancer between January 2020 and June 2020 at Nagasaki University Hospital. These were sliced at 2-mm intervals and washed with phosphate-buffered saline. 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. Hematoxylin and eosin (H&E) stained washed LNs were blindly examined by pathologists. Diagnoses based on SDB kit and automatic reader findings were compared with diagnoses made by histological examination of paraffin-embedded H&E stained sections of the LNs. Results: Six of the 117 LNs were assessed as positive and 111 as negative by histological examination. With a borderline CK19 absorbance of 50 milli-absorbance (mAbs) for detecting LN metastases excluding isolated tumor cells, the sensitivity, specificity, and overall agreement of the SDB kit were 66.7%, 99.1%, and 97.4%, respectively. Two patients with false-negatives had micrometastases of 0.6 and 0.5 mm in diameter. There was contamination by breast epithelial tissue in one false-positive case. With a borderline CK19 absorbance of 100 mAbs for distinguishing macrometastases from micrometastases, the sensitivity, specificity, and overall agreement of the SDB kit were 100%, 100%, and 100%, respectively. Furthermore, the kits and the automatic reader yielded diagnoses in approximately 20 min at a cost of less than 30 USD. 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. We plan to start a prospective multi-center study to evaluate clinical performance soon.
Citation Format: Ryota Otsubo, Hiroshi Yano, Megumi Matsumoto, Aya Tanaka, Ayako Fukushima, Sayaka Kuba, Michi Morita, Naoki Uno, Han-Seung Yoon, Katsunori Yanagihara, Susumu Eguchi, Takeshi Nagayasu. Evaluation of novel diagnostic kits using the semi-dry dot-blot method combined with an automatic reader for detecting metastases in lymph nodes of patients with breast cancer : A single-center prospective study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-39.