The diagnostic value of one step nucleic acid amplification (OSNA) in differentiating lymph node metastasis of tumors: A systematic review and meta-analysis

•The OSNA assay is useful to distinguish metastatic lymph nodes from non-metastatic ones in several tumor types.•250 copies/μl appeared to be an optimal cutoff value that distinguished between positive and negative lymph nodes.•CK-19 was selected as a useful mRNA marker for the OSNA assay.