Scientists have now discovered that esophageal cancer, the sixth most dangerous cancer type in the US, has a significant genetic basis. For the first time, specific gene variations have been identified for this type of cancer.
According to research published in the November 2008 issue of the journal Cancer Prevention Research, new variations in genes associated with esophageal cancer have been discovered. This is an example of what can be found by using new techniques in genome analysis and human genome mapping.
Esophageal cancer ranks sixth in cancer-related deaths (American Cancer Society, 2008). Risk factors associated with esophageal cancer include tobacco smoking, alcohol consumption, and GERD or reflux disease. More than 14000 people die each year because of Esophageal cancer in the United States alone.
The newly found variations in genes are related to "microRNAs (miRNAs)" writes the study's lead author, Dr. Xifeng Wu, Professor in the Department of Epidemiology of The University of Texas M. D. Anderson Cancer Center.
According to genetic experts, miRNAs are able to control approximately one-third of human genes. They have always believed that these miRNAs would be associated with the risk of developing certain kinds of cancer.
Researchers studied the relationships among 41 single-nucleotide polymorphisms (SNPs) in miRNA genes associated with an increased of esophageal cancer. SNPs are places in the DNA molecule where a single DNA chemical building block or nucleotide is changed.
More specifically, 346 patients participated in this study. These participants were recently diagnosed with esophageal cancer. Another 346 people, without cancer, were also recruited as a control group. Age, gender and ethnicity were all balanced in the study.
In the study, scientists showed that seven genotypes were significantly associated with esophageal cancer risk and four more may contribute to it, although the relationship is not clear-cut in these four genotypes, statistically speaking.
One of the most intriguing findings of this new study was that a single SNP in the mir423 region was associated with a significantly lower esophageal cancer risk. Basically, this SNP has a protective effect on patients who have it. Moreover, the protective effect of this newly found gene was significant for both smokers and non-smokers and for people 64 years old and younger. However, for people older than 64 years, the protective effect was not significant. More Interesting was the fact that the same mir423 region of the DNA is found in leukemia cells and in other diseases including heart disease and Alzheimer's disease.
The Importance of Genome Analysis and Genome Mapping
This is the first time that variations in genes related to microRNAs have been associated with esophageal cancer risk. As we learn more about our DNA with genome analysis techniques and as we progress with human genome mapping we would expect to find new variations in gene composition and new mutations. These will in turn help research and scientists develop new methods of cancer treatment to increase the rate of survival.
Xifeng Wu. November 2008. Cancer Prevention Research