Trend of morbidity and mortality of colorectal carcinoma in Nangang District of Harbin from 1992 to 2001

Relationship between the polymorphism of tumor necrosis factor-α-308 G>A and susceptibility to inflammatory bowel diseases and colorectal cancer: a meta-analysis. Eur J Hum Genet. 2011;19:432-437. [PMID: 21248737 DOI: 10.1038/ejhg.2010.159]

Inflammatory bowel disease (IBD) and colorectal cancer (CRC) are common health problems worldwide. Tumor necrosis factor (TNF) is a type of cytokine that induces inflammation and inhibits tumorigenesis. Several studies have assessed the relationship between the polymorphism of TNF-α-308 G>A and the susceptibility to IBD and CRC; however, the results have been controversial. In addition, the hypothesis whether the increased risk of CRC in IBD patients could be partly ascribed to the polymorphism of TNF-α-308 G>A was unclear. Therefore, we conducted this meta-analysis to confirm these associations. Pooled odd ratios (ORs) and 95% confidence intervals (95% CIs) were calculated on the basis of data from 14, 18, and 7 studies from a total of 27 studies for the associations between the polymorphism of TNF-α-308 G>A and ulcerative colitis, Crohn's disease (CD) and CRC. In Europeans, the AA genotype increased the risk of ulcerative colitis (UC) (OR, 2.041; 95% CI, 1.261-3.301) and CD (OR, 1.730; 95% CI, 1.168-2.564) significantly, without obvious heterogeneity and publication bias. Meanwhile, the GA genotype increased the risk of UC in Asians (OR, 2.360; 95% CI, 1.269-4.390) significantly. However, no significant association was observed for CRC in any ethnic population. The results of this meta-analysis suggested that the polymorphism of TNF-α-308 G>A participates in modifying the susceptibility to UC and CD in Europeans and Asians. The increased risk of CRC in IBD patients should be clarified as the combined effects of polymorphisms in TNF-α and other cytokines, and the interaction with environmental factors, in future studies.

Meta-analysis of different test indicators: Helicobacter pylori infection and the risk of colorectal cancer

BACKGROUND AND AIMS

Recent studies have demonstrated the relationship between Helicobacter pylori infection and the risk of colorectal carcinoma. However, the results of these studies remain controversial as the studies were relatively small in size and partially differed in designs, and so we reviewed the published studies and carried out a meta-analysis to further explore this relationship.

MATERIALS AND METHODS

We performed an extensive systematic review to find all the published case-control studies up to Jan. 2007 using electronic searching, hand searching, and reference lists of retrieved articles. Odds ratio (OR) was employed to evaluate the relationship of H. pylori infection and risk of colorectal cancer. Summary estimates were obtained using random effect models according to the result of a statistical test for heterogeneity across the studies. The presence of possible publication bias was assessed using different statistical approaches.

RESULTS

Thirteen studies were included, and summary OR 1.49 (95% confidence interval [CI] 1.17-1.91) was estimated for the association between H. pylori infection and colorectal cancer. Summary OR 1.56 (95% CI 1.14-2.14) was estimated for the association between immunoglobulin G antibody and colorectal cancer risk. By trimming and filling, the number of inputted studies was zero, and summary OR was still 1.49 (95% CI 1.17-1.91). The graphical funnel plot appeared asymmetrical, but there was no statistical evidence of publication bias. The method of fail-safe suggested that the effect of publication bias was small.

CONCLUSION

Current evidence, though limited, suggests that there is a possible increase in risk of colorectal cancer because of H. pylori infection.