Emerging role of long non-coding RNA MALAT1 in predicting clinical outcomes of patients with digestive system malignancies: A meta-analysis.

Digestive system malignancies are the most common cancer types worldwide and exhibit an extremely low overall 5-year survival rate. Therefore, clinically applicable biomarkers for predicting clinical outcome are urgently required. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is abnormally expressed in several cancer types. However, to the best of our knowledge, the association between MALAT1 expression and the prognosis of digestive system malignancies remains unknown. Therefore, the current study performed a meta-analysis to comprehensively summarize the association between MALAT1 expression and digestive system malignancies. A total of 1,157 Asian patients from 12 eligible studies [eight studies that investigated overall survival (OS), two studies that investigated disease-free survival and two studies that investigated both indicators] were analyzed. The present results identified a significant association between MALAT1 abundance and poor OS in patients with digestive system malignancies, with a pooled hazard ratio (HR) of 1.62 [95% confidence interval (CI), 1.35-1.88; P<0.001]. The tumor type, region, sample size and analysis type did not alter the predictive value of MALAT1 as an independent factor for survival. Furthermore, MALAT1 overexpression was an unfavorable prognostic factor for the overall survival of patients with esophageal carcinoma, pancreatic cancer, hepatocellular carcinoma and gastric cancer, with HRs of 1.89 (95% CI, 1.29-2.49), 1.76 (95% CI, 0.89-2.63), 1.46 (95% CI, 0.76-2.17) and 1.41 (95% CI, 1.04-1.78), respectively. In particular, increased MALAT1 expression levels were significantly associated with decreased OS in patients with colorectal cancer (HR, 3.04; 95% CI, 1.77-4.31). In conclusion, lncRNA MALAT1 may be a potential prognostic factor for digestive system malignancies in Asian populations.