People with the mutation for hereditary hemochromatosis are at significantly higher risk for colon cancer
People who carry the mutation for hereditary
hemochromatosis are 40 percent more likely than other people to develop
colon cancer, according to an article in the January 15th issue of
the Journal of the National Cancer Institute. "Our
findings are consistent with the view that taking in too much iron
may be an environmental risk factor for colon cancer in some people,"
said Nicholas J. Shaheen, M.D., lead author of the study.
Iron is a pro-oxidant, which
means high iron levels can lead to free radical formation and DNA
damage, said Shaheen and his coauthors. The authors added that iron
is an essential element for tumor cell growth and proliferation.
Mutations in the gene abbreviated
as HFE are common, with a prevalence of roughly 15 percent of the
U.S. population, according to Shaheen. Two such mutations investigated
in the current study are strongly associated with the development
of hereditary hemochromatosis. The gene itself encodes a cellular
signaling protein that plays a role in iron metabolism.
"We don't fully understand
why some people develop colon cancer and others do not," Shaheen
said. "Our goal was to look for genetic risk factors for the
disease that might be easily identifiable."
A total of 1,300 adults aged
40 to 79 years were involved in this population-based, case-control
study, including people with and without colon cancer. Participants
provided information on total iron intake and use of non-steroidal
anti-inflammatory drugs. Blood samples were provided, and DNA was
extracted and analyzed for the two major HFE mutations.
After controlling for age,
race, gender, red meat consumption, non-steroidal anti-inflammatory
drug use, and total iron intake, study participants with any HFE
mutation were found to be 1.4 times more likely to have colon cancer
than participants with no HFE mutation. The risk of colon cancer
associated with an HFE mutation was similar for people with and
without a family history of colon cancer. In addition, cancer risk
increased with increasing age and total iron intake among people
with an HFE mutation.
"When you have a high
number of people with the mutation, and although the mutation itself
confers only a mildly increased risk, the total number of cancers
that may be attributed to HFE mutations could be fairly high,"
Shaheen said.
He added that further research
on other populations is needed. "If we can develop a panel
of adequate markers that really lets us identify a high-risk group,
we can concentrate our colon cancer screening and surveillance in
that group."
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