Expression of Raf kinase inhibitor protein and radiotherapy prognosis of non-small-cell lung cancer

Background: Raf kinase inhibitor protein (RKIP) is thought to be an inhibitor of multiple cellular signaling pathways and a suppressor of cancer metastasis in a variety of human cancers. However, function of RKIP in non-small cell lung cancer (NSCLC) is not yet completely understood. The purpose of this study was to investigate the relationship between the RKIP expression in tumor tissues of NSCLC and the prognosis of NSCLC patient following radiotherapy (RT). Methods: The level of RKIP expression in tumor tissue samples from 77 NSCLC patients was retrospectively determined by using immunohistochemistry. Survival rate was estimated by Kaplan-Meier curves. Log-rank univariate analysis was used to identify the factors with prognostic significance and the results were verified by multivariate Cox proportionate hazard regression analysis. Results: Among the 77 NSCLC patients, 62 (80.5%) patients had low RKIP expression and 15 (19.5%) had high expression. The 1-, 2- and 3- year survival rates were 62.3% (48/77), 40.3% (24/77) and 27.3% (4/77), respectively. The Cox regression model showed that patients in low RKIP expression group had a significantly higher risk of death (RR = 2.141) than those in high RKIP expression group (P < 0.05). Multivariate analyses revealed RKIP expression was an independent factor that affected overall survival (P < 0.05). Conclusion: RKIP could be a potential biomarker for the prognosis of NSCLC patients after RT.