A Comparison of Approaches for Association Studies of Polymorphisms and Colorectal Cancer Risk.

Publication Type:

Journal Article


Colorectal disease : the official journal of the Association of Coloproctology of Great Britain and Ireland (2012)


2012, March 2012, Public Health Sciences Division


Aim:  Meta-analyses have evaluated associations between polymorphisms and colorectal cancer risk, but the quality of individual studies used to inform them may vary substantially. Our aim was to apply well-established quality-control criteria to individual association studies, and then compare the results of meta-analyses that included or excluded studies that did not meet these criteria. Method:  We used meta-analyses of studies reporting a relationship between polymorphisms and colorectal cancer published between 1996 and 2008. Polymorphism-cancer associations were derived in separate meta-analyses including only those meeting quality-control criteria. Results:  Relative odds ratios varied substantially between the open and restricted group meta-analyses for all variants except MTHFR 677 CT. However, the associations were modest and the direction of relative risk did not change after applying criteria. Publication bias was detected for all associations, except the restricted set of studies for GSTP1 GG. Conclusion:  We observed variation in calculated relative risk and changes in tests for publication bias depending on inclusion criteria used for association studies of polymorphisms and colorectal cancer. Standardizing study inclusion criteria may reduce the variation in findings for meta-analyses of gene-association studies of common diseases such as colorectal cancer. © 2012 The Authors Colorectal Disease © 2012 The Association of Coloproctology of Great Britain and Ireland.