In the past two decades, approximately 1000 reports have been published regarding associations between genetic variants in candidate genes and risk of colorectal cancer (CRC).
Study results are inconsistent.
Professor Wei Zheng and colleagues from Tennessee, USA provided a synopsis of the current understanding of genetic factors for colorectal cancer risk through systematically evaluating results from previous studies.
The team searched PubMed and Google Scholar to identify papers that investigated associations between genetic variants and colorectal cancer risk and published through 2012.
With data from 950 papers, the team conducted 910 meta-analyses for 267 genetic variants in 150 candidate genes with at least 3 data sources.
The researchers used Venice criteria and false-positive report probability tests to grade levels of cumulative epidemiological evidence of significant associations with colorectal cancer risk.
|62 variants in 50 candidate genes showed an association with colorectal cancer risk|
The team identified 62 variants in 50 candidate genes that showed a nominally significant association with colorectal cancer risk.
Cumulative epidemiological evidence for a significant association with colorectal cancer risk was graded strong for 8 variants in 5 genes, moderate for 2 variants in 2 genes, and weak for 52 variants in 45 genes.
Additionally, 40 variants in 33 genes showed convincing evidence of no association with colorectal cancer risk in meta-analyses including at least 5000 cases and 5000 controls.
Professor Zheng's team concludes, "Approximately 4% of genetic variants evaluated to date in candidate-gene association studies showed moderate to strong cumulative epidemiological evidence of an association with colorectal cancer risk."
"These genetic variants, if confirmed, may explain approximately 5% of familial colorectal cancer risk."