Abstract P2-01-31: Validation of novel diagnostic kits using the semi-dry dot-blot method for detecting metastatic lymph nodes in breast cancer; distinguishing macrometastases and micrometastases

Abstract

Abstract Background: The semi-dry dot-blot (SDB) method is a diagnostic procedure for detecting lymph node (LN) metastases. Metastases are confirmed by the presence of cytokeratin (CK) in lavage fluid of sectioned LNs that contain anti-pancytokeratin antibody, based on the theory that epithelial components such as CK are not found in normal LNs. We evaluated two novel SDB kits that use the newly developed anti-CK19 antibody for diagnosing LN metastases in breast cancer. Methods: We obtained 159 LNs dissected from 93 breast cancer patients from July 2013 to December 2015 at Nagasaki University Hospital, including 38 dissected axillary LNs and 121 sentinel LNs, sliced at 2-mm intervals and washed with phosphate-buffered saline. The suspended cells in the lavage fluid of sliced LNs were centrifuged and lysed to extract protein. This extracted protein was used with a low-power and a high-power kit to diagnose LN metastasis. The washed LNs were blindly diagnosed by pathologists using hematoxylin and eosin (H&E) stain. Diagnoses based on the kit were compared with their H&E counterparts. Results: Of the 159 LNs, 68 were assessed as positive and 91 as negative by permanent pathological examination with H&E. Sensitivity, specificity, and accuracy of the low-power kit for detecting LN metastases was 83.8%, 100%, and 93.1%, respectively. In 11 false-negative cases, there were nine micrometastases, producing a sensitivity of 96.4% for detecting macrometastases. Sensitivity, specificity, and accuracy of the high-power kit for detecting LN metastases was 92.6%, 92.3%, and 92.5%, respectively. Combining the low- and high-power kit results, sensitivity, specificity and accuracy for distinguishing macrometastases from micrometastases was 94.5%, 95.2%, and 95.0%, respectively. Diagnosis was achieved in approximately 20 min using the kits, at a cost of less than 25 USD. Conclusions: The kits in our study were accurate, quick, and cost-effective in diagnosing LN metastases without the loss of LN tissue. The kits' ability to distinguish macrometastases from micrometastases was excellent, which is important, clinically. Citation Format: Otsubo R, Hirakawa H, Oikawa M, Inamasu E, Baba M, Matsumoto M, Yano H, Kinoshita N, Abe K, Fukuoka J, Nagayasu T. Validation of novel diagnostic kits using the semi-dry dot-blot method for detecting metastatic lymph nodes in breast cancer; distinguishing macrometastases and micrometastases [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-01-31.