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.
We obtained 139 LNs dissected from 79 breast cancer patients from July 2013 to April 2015 at Nagasaki University Hospital, including 32 dissected axillary LNs and 107 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.
Of the 139 LNs, 55 were assessed as positive and 84 as negative by permanent pathological examination with H&E. Sensitivity, specificity, and accuracy of the low-power kit for detecting LN metastases was 80.7%, 100%, and 92.2%, respectively. In 10 false-negative cases, there were eight micrometastases, producing a sensitivity of 95.3% for detecting macrometastases. Sensitivity, specificity, and accuracy of the high-power kit for detecting LN metastases was 90.9%, 91.7%, and 92.1%, respectively. Combining the low- and high-power kit results, sensitivity, specificity and accuracy for distinguishing macrometastases from micrometastases was 95.3%, 95.8%, and 95.7%, respectively. Diagnosis was achieved in approximately 20 min using the kits, at a cost of less than 25 USD.
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.
Clinical trial identification
Legal entity responsible for the study
Nagasaki University Hospital, Department of Surgical Oncology
All authors have declared no conflicts of interest.