Serum sRANKL and sRANKL/OPG ratio: Novel biomarkers in non-small cell lung cancer.

Osteoprotegerin (OPG) and soluble receptor activator of nuclear factor-κB ligand (sRANKL) are bone-regulating molecules. The two molecules have each been indicated to be involved in carcinogenesis. However, the diagnostic significance in non-small cell lung cancer (NSCLC) remains to be investigated. Thus, the objective of the present study was to investigate the serum levels of OPG and sRANKL in NSCLC patients, and to analyze their clinical significance. Serum OPG and sRANKL levels were determined in 50 patients with NSCLC, matched with 25 patients with benign lung nodule and 25 healthy controls by enzyme-linked immunosorbent assay. The level of serum sRANKL and the sRANKL/OPG ratio were significant elevated in the patients with NSCLC compared with the benign lung nodule patients and the healthy controls. Receiver operating characteristic curves were used to evaluate the performance of sRANKL and sRANKL/OPG. When the cut-off values for the sRANKL level and the sRANKL/OPG ratio were set at 4.20 pmol/l and 0.60, respectively, the sensitivity, specificity and accuracy of sRANKL were 74.0, 84.0 and 77.3%, respectively. Moreover, the sensitivity, specificity and accuracy of the sRANKL/OPG ratio were 84.0, 88.0 and 85.3%, respectively. On the other hand, when the cut-off values of the serum sRANKL level and the sRANKL/OPG ratio were set at 5.24 pmol/l and 0.63, respectively, the sensitivity, specificity and accuracy of sRANKL were 60.0, 84.0 and 68.0%, respectively. The sensitivity, specificity and accuracy of the ratio were 78.0, 64.0 and 73.3%, respectively. The OPG/RANKL system may be involved in the pathogenesis of NSCLC. More importantly, the serum sRANKL level and the sRANKL/OPG ratio may have the potential to be novel biomarkers for the diagnosis of NSCLC.