OSNA for detection of sentinel lymph node metastasis.

Abstract

74 Background: SLN (sentinel lymph node) biopsy is a common procedure in surgical treatment of clinically node-negative breast cancer. OSNA (One-step nucleic acid amplification) is a semi-automated examination using molecular biological technique, and OSNA allows straightforward diagnosis of SLN metastasis without a pathologist by quantitative evaluation of CK19 m-RNA. The objective of this study was to confirm the reliability of OSNA for detection of sentinel Lymph node metastasis, and OSNA is also useful even in neoadjuvant chemotherapy (NAC) patients. Methods: Surgically obtained 159 SLNs from 106 breast cancer patients were evaluated and compared. The SLNs were sectioned into three pieces along the major axis. The central piece was sent to pathologists in an outside laboratory for postoperative histological investigation to diagnose metastasis. The other two pieces were examined with the OSNA to detecting metastasis during an operation. The OSNA analysis and the histological investigation were compared. Then, the patients were divided into two groups, one group was the patients with NAC (22 SLNs from 13 patients), and another group was the patients without NAC (137 SLNs from 93 patients). It was examined whether those concordance rates were similar. Results: 151 SLNs were same diagnosis using both methods. 4 SLNs were negative on OSNA but positive on histology, and these 4 SLNs contained only micrometastasis lesion. Other 4 SLNs were positive on OSNA but negative on histology. The concordance rate was 95.0%. In the patients with NAC, 20 SLNs were same diagnosis. Two SLNs were negative on OSNA but positive on histology, and these 2 SLNs were micrometastasis. The concordance rate was 90.9%. In the patients without NAC, 131 SLNs were same diagnosis. 2 SLNs were positive on OSNA but negative on history, and these 2 SLNs were micrometastasis. 4 SLNs were positive on OSNA but negative on history. The concordance rate was 95.6%. Conclusions: The concordance rate in patients with NAC was as high level as the rate in patients without NAC. The false negative SLNs were all micrometastasis. These results suggest that OSNA is very useful for detecting SLN metastasis and it is clinically acceptable in NAC patients.