Well Done Red Meat Does Not Appear to Increase Risk of Breast Cancer, UC Irvine Study Finds
Results counter previous findings showing link between breast cancer and eating fully cooked meats
Irvine, Calif., March 28, 2000 — Eating well-done red meat prepared with
such high-temperature cooking methods as grilling and frying does not appear to increase
the risk of breast cancer, according to a UC Irvine College
of Medicine study that also found that eating greater amounts of thoroughly cooked
white meats such as chicken appears to protect against the disease.
The study counters previous findings that reported a link
between breast cancer and eating well-done meats.
Dr. Ralph J. Delfino, assistant professor of epidemiology,
and Hoda Anton-Culver, professor of epidemiology, led a research team that found that a
gene suspected of metabolizing cancer-causing chemicals on the surface of well-done meats
had no link to breast cancer. Women who ate well-done red meat such as pork or beef had no
increased risk of breast cancer, and women who ate chicken had half the risk of breast
cancer compared with women who did not eat as much white meat. The findings appear in the
April issue of Carcinogenesis.
"No matter how the food was prepared—blackened,
barbecued, grilled or pan-fried—red meat didn't increase the risk, and white meat
actually seemed to offer protection against breast cancer," Delfino said.
"Although previous studies showed chemicals found on the surface of these foods have
caused mammary cell cancers in rats, we didn't see it happening in humans. However, this
study cannot rule out that these foods may add to the risk of colon and stomach
cancers."
The researchers compared the diets of 114 women with breast
cancer with those of 280 women who had benign breast growths. They were questioned on
their diet of red meat, which included hamburgers, beefsteak, pork chops, bacon and
breakfast sausage. White meat eaten included chicken, turkey or fish (shellfish were not
included).
The researchers looked for activity of a gene that produces
an enzyme in the blood known as NAT2. In previous studies involving rats, this NAT2 enzyme
activated cancer-causing chemicals that are produced on the surface of meats by
high-temperature cooking methods such as grilling and frying. The NAT2 enzyme helped the
cancer-causing chemicals—called heterocyclic aromatic amines—bind to DNA, a
process that induced cancer in rats.
However, in the UCI study, levels of the NAT2 enzyme were no
different among women with breast cancer than among women with benign
growths—regardless of the types of red meat consumed.
Women who ate more than 67 grams of white meat daily,
however, had half the risk of breast cancer compared to women eating one-third that
amount, less than 26 grams a day. This effect was seen even among women who ate pan-fried
or barbecued chicken, which are known to have high amounts of heterocyclic aromatic
amines. It was not clear from the study what may be causing this protective effect.
"Our study shows that the causes of cancer are often
much more complex than they may appear from animal studies. We have to be very cautious in
interpreting these results, since our study included a small number of participants,"
Anton-Culver said. "We need to expand this investigation to compare our findings with
those of women who are free of any breast disease."
The researchers are now looking at other genes that may play
a role in metabolism and either increase or decrease the risks of getting cancer. The
research was conducted through the UCI Center for Cancer Genetics Research and Prevention,
which is directed by Anton-Culver. The research was funded by the University of California
Breast Cancer Research Program.
The Center for Cancer Genetics Research and Prevention is
part of UCI's Biomedical Research Center, located on the western campus in the College of
Medicine. The research center is providing much-needed laboratory and clinical facilities
for UCI researchers focusing on the major health challenges of the 21st century. When
complete, the center will focus on research in the neurosciences, the genetics of cancer,
immunology and infectious disease and clinical trials. The center's first building, the
Gillespie Neuroscience Research Facility, is home to the Reeve-Irvine Research Center and
the Institute for Brain Again and Dementia. Construction of the second building, the
Robert R. Sprague Family Foundation Hall, began in February.
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