Prognostic value of long noncoding RNA MALAT1 in various carcinomas: evidence from nine studies

RNA-sequencing technology is progressing day by day. Numerous researches have showed that long noncoding RNAs (lncRNAs) play oncogenic or tumor suppressor roles in tumor biological processes. To our knowledge, many studies have identified a lot of lncRNAs with aberrant expression in several types of cancers. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a newly discovered lncRNA, has been reported that is overexpressed in several types of cancers. But the clinical value of MALAT1 in cancers remains unclear. Therefore, in this present study, we aimed to investigate potential clinical application role of MALAT1 as a prognostic biomarker in malignant tumors. We performed a detailed search in PubMed, Embase, Medline, and Cochrane Library until July 2015. According to the inclusion and exclusion criteria, nine studies with a total of 941 patients were selected to explore the relationship between high expression of MALAT1 and overall survival in cancers. The result showed that overexpression of MALAT1 could predict poor overall survival (OS) in cancer patients, with pooled hazard ratio (HR) of 1.90 [95 % confidence interval (CI) 1.68-2.16, P < 0.0001]. In conclusion, the present meta-analysis demonstrated that high expression of MALAT1 might be served as a novel prognostic biomarker in different types of cancers.