The association between osteopontin and survival in non-small-cell lung cancer patients: a meta-analysis of 13 cohorts.

In the last decade, osteopontin (OPN) was identified as one of the important proteins that promote the metastasis of tumor. However, the association between OPN overexpression and clinical outcome of non-small-cell lung cancer (NSCLC) was unclear. The purpose of this study is to investigate the role of OPN in NSCLC patients. A total of 13 studies are included to explore the relationship between the OPN elevation and the overall survival (OS) and disease-free survival (DFS) in NSCLC patients. We searched for related articles in PubMed, Web of Science, Google Scholar, and Cochrane Library databases, which were published before January 31, 2015. Hazard ratio (HR), odds ratio (OR), and 95% confidence interval (CI) in the high OPN expression group compared with the low OPN expression group were calculated and analyzed. Primary results were summarized by using a fixed-effects model or a random-effects model. The stratified analyses in subgroups were also performed. Thirteen cohort studies, which involved 1,630 patients, were included. Subgroup analyses were performed by area and test method of OPN. We found that OPN was significantly associated with poor OS (HR =2.20, 95% CI 1.71-2.83, P<0.001) and DFS (HR =2.11, 95% CI 1.62-2.74, P<0.001) in NSCLC patients. OPN overexpression tended to be associated with the presence of advanced tumor TNM stage (III and IV) (OR =2.57, 95% CI 1.61-4.11, P<0.001). The Egger's test suggested that there was no publication bias in OS studies (P=0.062) and DFS studies (P=0.740). These data indicate that OPN seems to have a significant predictive potential in estimating survival in NSCLC.