To systematically evaluate whether the expression level of LncRNA is associated with the clinicopathological features and prognostic value for gastric cancer.

The Chinese databases including CNKI, CBM, WanFang Databases, VIP Databases, and the English databases including EMbase, PubMed, Cochrane Library (Issue 4, 2017) and Web of Science were systematically searched with the search time end in April 2017. All eligible studies associated with downregulated LncRNA and prognosis in gastric cancer were included. Two researchers independently screened the included studies, extracted data and evaluated the quality. The STATA 12.0 software and Begg's, Egger's funnel maps were used for Meta-analysis and evaluation of publication bias.

A total of six studies about 594 gastric cancer patients which showed the relationship between the low expression level of LncRNA were finally included, and all the tissue samples were from China. The expression level of LncRNA was associated with TNM staging (RR=2.06, 95% CI=1.73-2.46, P=0.001) , the depth of invasion (RR=2.73, 95% CI =2.17-2.43, P=0.001) and the number of lymph node metastases (RR=1.63, 95% CI=1.37-1.94, P=0.001) . There was significant difference in overall survival among the 5 groups (I²=68.9%, P=0.012) , whereas low-regulated LncRNA which showed a shorter overall survival (HR=0.56, 95% CI=0.31-0.99, P=0.046) was statistically significant. There was significant difference in disease free survival among the three studies (I²=71.0%, P=0.032) , while no significant difference between the high-expression group and the low-expression group of LncRNA (HR=0.57, 95% CI=0.32-1.03, P=0.061) . The effects of the 6 studies on the combination of HR and the possibility of publishing bias were small (Egger's, P=0.651; Begg's, P=0.806) .

Low expression of LncRNA is a predictive risk factor for poor prognosis in gastric cancer patients. The expression level of LncRNA is closely related to TNM stage, depth of tumor invasion and regional lymph node metastasis in patients with gastric cancer.