The accurate diagnosis of lymph node (LN) metastasis is important for making treatment decisions for gastric cancer patients. This multicenter study evaluated the clinical performance of the one-step nucleic acid amplification (OSNA) assay (Sysmex Corp.), an automated system that detects cytokeratin 19 (CK19) mRNA, in detecting LN metastases in gastric cancer patients.
LNs retrieved from patients who had undergone gastric cancer surgery at one of the four Japanese hospitals involved in this study were divided into blocks at 2-mm intervals. Alternate blocks were examined with the OSNA assay and the remaining blocks were assessed histologically.
A total of 394 LNs from 61 patients were examined. The concordance rate between the OSNA assay and the histological examination was 0.942 (95 % CI, 0.914–0.963). Sensitivity and specificity of the OSNA assay compared to the histological examination were 0.833 (95 % CI, 0.707–0.921) and 0.959 (95 % CI, 0.932–0.977), respectively. Discordant results were observed in 23 LNs (5.8 %), and these were mainly the result of tissue allocation bias and/or low CK19 protein expression.
The OSNA assay can detect lymph node metastases in gastric cancer patients as accurately as the histological examination of blocks sectioned at 2-mm intervals. The OSNA assay is a useful tool for the intraoperative diagnosis of LN metastasis in gastric cancer patients.