Matrix metalloproteinase-9 (MMP-9) is an important member of the matrix metalloproteinase family and is considered to be involved in the invasion and metastasis of cancer cells. Many studies were published to assess the prognostic role of MMP-9 overexpression in patients with colorectal cancer, but the findings from those studies were inconsistent. We searched eligible studies in Pubmed, Embase, and Web of Science databases. Thirteen studies with a total of 2, 390 CRC patients were finally included into the meta-analysis. The pooled hazard ratios (HRs) with the corresponding 95 % confidence interval (95 % CIs) for overall and progression-free survival were calculated by using meta-analysis. There were nine studies with a total of 1,674 colorectal cancer patients relating the progression-free survival, and eight studies with a total of 1,379 colorectal cancer patients relating the overall survival. Overall, MMP-9 overexpression was associated with poorer progression-free survival in patients with colorectal cancer (fixed-effects HR 1.81, 95 % CI 1.48-2.20, P < 0.001; random-effects HR 1.92, 95 % CI 1.46-2.53, P < 0.001). In addition, MMP-9 overexpression was also associated with poorer overall survival in patients with colorectal cancer (fixed-effects HR 1.74, 95 % CI 1.39-2.19, P < 0.001; random-effects HR 1.78, 95 % CI 1.31-2.41, P < 0.001). MMP-9 expression is associated with the prognosis of patients with colorectal cancer, and patients with higher MMP-9 expression have poorer survival.

This meta-analysis was performed to evaluate the role of CDH1 promoter methylation in colorectal carcinogenesis. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library, and CBM databases were searched for relevant articles published before November 1st, 2013 without any language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated. Nine clinical cohort studies met all our inclusion criteria and were included in this meta-analysis. A total of 883 colorectal cancer (CRC) patients were assessed. Our meta-analysis results revealed that the frequencies of CDH1 promoter methylation in CRC tissues were higher than those in control tissues (OR=2.61, 95% CI=1.24-5.50, p=0.012). A subgroup analysis by ethnicity showed that CDH1 promoter methylation was closely linked to the pathogenesis of CRC among Asians and Africans (Asians: OR=2.90, 95% CI=1.26-6.67, p=0.012; Africans: OR=3.81, 95% CI=1.56-9.34, p=0.003; respectively), but not among Caucasians (OR=1.68, 95% CI=0.24-11.72, p=0.598). A further subgroup analysis by type of control tissues suggested that CRC tissues also exhibited higher frequencies of CDH1 promoter methylation than those of normal and adjacent tissues (normal: OR=1.57, 95% CI=1.12-2.21, p=0.009; adjacent: OR=5.07, 95% CI=2.91-8.82, p<0.001; respectively). However, we found no evidence for any significant difference in the frequencies of CDH1 promoter methylation between CRC tissues and adenomas tissues (OR=1.18, 95% CI=0.74-1.90, p=0.485). Our findings provide empirical evidence that CDH1 promoter methylation may play an important role in colorectal carcinogenesis. Thus, CDH1 promoter methylation may be a useful biomarker for the early diagnosis of CRC.

The aim of the present meta-analysis was to evaluate the correlation between a common polymorphism, rs13361189 C>T in the immunity-related GTPase M (IRGM) gene, and susceptibility to Crohn’s disease (CD). The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library and CBM databases were investigated from database inception through to October 1, 2013 without the application of any language restrictions. The meta-analysis was performed using STATA 12.0 software and the relative risk (RR) with a 95% confidence interval (CI) was calculated. Seven case-control studies were included with a total of 3,093 CD patients and 3,227 healthy control subjects. The results of the meta-analysis revealed that the IRGM rs13361189 polymorphism correlates with an increased risk of CD (T allele versus C allele: RR=1.25 with 95% CI, 1.04–1.50; P=0.016 and CT + TT versus CC: RR=1.21 with 95% CI, 1.03–1.42; P=0.018). A subgroup analysis conducted using a genotyping method indicated that the IRGM rs13361189 polymorphism was correlated with an increased risk of CD in the TaqMan® (T allele versus C allele: RR=1.32 with 95% CI, 1.01–1.73; P=0.042) and the polymerase chain reaction-restriction fragment length polymorphism subgroups (T allele versus C allele: RR=1.80 with 95% CI, 1.32–2.45; P<0.001 and CT + TT versus CC: RR=1.61 with 95% CI, 1.19–2.18; P=0.018). However, no correlation was observed in the direct sequencing subgroup (P>0.05). Further subgroup analysis by sample size demonstrated significant correlations between the IRGM rs13361189 polymorphism and an increased risk of CD in the large sample-size subgroup (T allele versus C allele: RR=1.46 with 95% CI, 1.26–1.68; P<0.001 and CT + TT versus CC: RR=1.40 with 95% CI, 1.21–1.62; P<0.001). However, no correlation was identified between the IRGM rs13361189 polymorphism and CD risk in the small sample-size subgroup (P>0.05). The present meta-analysis indicated that the IRGM rs13361189 polymorphism may contribute to susceptibility to CD. Thus, IRGM rs13361189 polymorphism may be a potential biomarker for the early diagnosis of CD.