Several studies published this month by research teams studying populations all over the world report finding a significant link between a gene on human chromosome 8 and the risk of developing colon cancer.
One of these studies is part of a ten-year project between Michigan in the US and Israel called the Molecular Epidemiology of Colorectal Cancer involving thousands of Israeli Jews and Arabs. The study is published in the July issue of Cancer Biology and Therapy.
Researchers from the University of Michigan (U-M) Medical School and U-M School of Public Health, the Catalan Institute of Oncology in Spain, the CHS National Israeli Cancer Control Center and Technion (the Israel Institute of Technology) compared the genetic material and family history of 1,800 colorectal cancer patients and 1,900 healthy people. Both groups had the same distribution of age, gender and ethnicity which was either Ashkenazi Jew, Sephardic Jew or Arab/non-Jew.
They also tested tumour tissue from many of the cancer patients.
The results showed that people who carry a genetic variation known as the C allele of rs10505477 were 23 per cent more likely to have colon cancer than those without it. The genetic variant is located on a small area of chromosome 8 called 8q24.
The 8q24 link was particularly strong for those patients diagnosed with colon cancer before they reached the age of 50.
The researchers concluded that this variation may account for 14 per cent of colorectal cancer cases in Israel, where colon cancer is the leading cause of death among cancer patients.
Other research teams are reporting similar findings about 8q24 in other populations, suggesting this genetic marker is significant across ethnic groups. Those studies are published in the journal Nature Genetics.
One of the co-leaders of the Michigan Israeli team and first author of the paper is Dr Stephen Gruber, an associate professor of internal medicine and of human genetics in the U-M Medical School, and of epidemiology in the U-M School of Public Health. He also leads the Cancer Genetics program in the U-M Comprehensive Cancer Center, which examines inherited cancer risks.
Gruber said the new discovery was particularly interesting when taken together with other recent findings about this genetic region in prostate and breast cancer:
“The same genetic region that predisposes to colon cancer has also recently been shown to be an important region predisposing to breast cancer and prostate cancer.”
“The specific genetic cause for this joint susceptibility to three different cancers has not yet been discovered, but several groups are working to close in on the mechanism that might cause these cancers,” he added.
This is yet another in a series of genetic studies that have been unravelling links between disease susceptibility and particular gene variants since the human genome was sequenced in 2003.
“The mystery of the relationship between our genetic code and disease is now starting to become clear, and many scientists are turning to the same chapter to find important clues to colorectal cancer,” said Gruber.
Gruber and colleagues will be conducting further research in this area.
The researchers said that while there was no genetic screening test for the variant they have discovered, there are tests for other variants known to be linked to colon cancer.
They said that people with a strong family history of colon cancer, particularly if their relatives got it while young, before they reached the age of 50, should be screened, have a colonoscopy and genetic counselling before they too reached the age of 50.
“Colon cancer is one of the most common cancers in the United States, and the good news is that it’s largely preventable with early screening,” said Gruber.
According to the American Cancer Society, 150,000 new cases of colon cancer will be diagnosed in the United States in 2007, and more than 50,000 Americans will die from it.
“Genetic Variation in 8q24 Associated with Risk of Colorectal Cancer.”
Stephen B. Gruber, Victor Moreno, Laura S. Rozek, Hedy S. Rennert, Flavio Lejbkowicz, Joseph D. Bonner, Joel K. Greenson, Thomas J. Giordano, Eric R. Fearon and Gad Rennert.
Cancer Biology and Therapy, Volume 6, Issue 7, July 2007
Written by: Catharine Paddock
Writer: Medical News Today