Cancer Red meat raises risk of cancer of small and large intestines
By David Liu Ph.D.
Nov 24, 2008 - 8:28:58 AM
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Monday Nov 24 2008 (foodconsumer.org) -- Eating red meat
and processed meat may increase risk of cancer in the small intestine,
according to an observational study published in the current issue of the
journal Cancer Research.
During the 8-year study of nearly half a million men and
women, Amanda Cross, Ph.D., a National Cancer Institute researcher and the
study's lead author, found 60 cases of adenocarcinomas and 80 cases carcinoid
tumors of the small intestine were recorded.
There was no clear connection between red and processed
meat and these tumors, but Cross and colleagues suggested a noticeably elevated
risk for carcinoid tumors in the small intestine in association with saturated
fat intake
Evidence also suggests that cancers of the small and
large bowel both arise from adenomatous polyp precursor lesions and the large
intestine is more susceptible to carcinogenesis.
Cancer of the small intestine is rare, but the incidence
has been increasing since 1970s.
People
who develop this cancer are more likely than others to also develop a second
primary cancer such as colorectal cancer, according to Cross and colleagues.
Another study published in the Nov 2008 issue of Cancer
epidemiology, biomarkers & prevention suggested that eating lots of meat
may increase colorectal cancer regardless of genotypes of certain genes
involved in the metabolism of carcinogens formed in overcooked meat.
The case-control study led by Cotterchio M and colleagues
from Cancer Care Ontario in Toronto, Canada found those who ate more than 5
servings of meat per week were 67 percent more likely to develop colorectal
cancer than those who ate 2 or less than 2 servings per week.
For the study, the researchers surveyed 1,095 patients
age 20 to 74 who were diagnosed with colorectal cancer between 1997 and 2000
and 1,890 age- matched control using epidemiologic and food questionnaires.
Blood samples from 842 cases and 1,252 controls were also
analyzed for genetic variants in 15 enzymes involved in the metabolism of
cancer-causing agents formed in overcooked meat including cytochrome P450,
glutathione S-transferase, UDP-glucuronosyltransferases, SULT, NAT, mEH, and
AHR.
The researchers found red meat consumption was associated
with a 67 percent increased risk of colorectal cancer while the cancer risk in
those who ate more than 2 servings per week was increased by 57 percent
compared to those who ate 2 or less than 2 servings per week.
They said CYP2C9 and NAT2 variants were associated with
colorectal cancer risk.
And they found
red meat intake was associated with elevated colorectal cancer risk regardless
of the statuses of their genotypes.
However, they also found that persons with CYP1B! and
SULT1A! Variants were at the highest risk of the cancer. And well-done red meat
intake was associated with an elevated risk of colorectal cancer regardless of
carcinogen-metabolizing genotype.