[MOL] Internet Home - American Association for Cancer Research (AACR)

[Martin Auslander <fitecancer@earthlink.net>]

Good Day FRiends,

Thought this might be of interest.


file:///C|/windows/temp/nscomm40/tmp/tmp2/edt1.htm

God Bless you,
marty auslander

Title: Internet Home - American Association for Cancer Research (AACR)

  New Research Explores Relationship of Cooked-Meat Carcinogens and Breast
                               Cancer

              Research Results from AACR 91st Annual Meeting

 SAN FRANCISCO, April 1, 2000 -- Cooking meat at high temperatures produces
 heterocyclic amines (HCAs) and polycyclicnaromatic hydrocarbons (PAHs), compounds
 known to promote the development of cancer in animals. Three new studies presented at
 the 91st Annual Meeting of the American Association for Cancer Research (AACR)
 explore the relationship of HCAs and PAHs to breast cancer and expand the growing
 body of literature on the role of food preparation methods in carcinogenesis.

 Study Suggests Possible Connection Between Compound in Cooked Meat and
 Breast Cancer

 Data from a new collaborative study between researchers of the Iowa Women's Health
 Study and NCI investigators connect PhIP, a heterocyclic amine, with increased risk for
 breast cancer. HCAs are the by products of a reaction between amino acids, a core
 component of protein, and creatine, a chemical in muscles. The HCA-producing reaction
 is triggered when food from animal muscle -- beef, pork, poultry and fish -- is cooked at
 high temperatures (300-400°F). Frying, broiling, and barbecuing generate the most HCA;
 the longer the meat is cooked, the more HCAs result.

 From questionnaires completed by participants in the Iowa Women's Health Study about
 the amount of meat they ate and how it was prepared, researchers estimated the amount
 of three different HCAs in respondents' diets: PhIP, MeIQx, and DiMeIQx. Only PhIP,
 the principal HCA tied to breast cancer in animal models, showed a correlation with risk
 of breast cancer in the study population.

 "The association we found appears to be an effect of meat preparation, not total meat or
 red meat consumption; a little liquid around the meat may help reduce the production of
 these chemicals," said Rashmi Sinha, Ph.D., investigator, Nutritional Epidemiology
 Branch, Division of Cancer Epidemiology and Genetics at NCI in Bethesda, MD. Dr.
 Sinha cautioned that these findings are "suggestive rather than definitive" and that more
 research is needed to establish a clear relationship between PhIP and breast cancer.

 A total of 273 breast cancer patients and 657 control subjects completed the questions,
 aided by photographs defining degrees of cooking from rare through very well-done. In
 this and other studies of the HCA-cancer connection, the red meat category includes
 pork.

 Cancer-Causing Agent Masquerades as Weak Estrogen in Human Cells

 Another study that found PhIP to behave like a female sex hormone in laboratory tests
 may shed light on the association of this well-known carcinogen with breast cancer in rats,
 but researchers conclude that, on the basis of currently available data, PhIP's estrogenic
 activity in humans is negligible.

 Some therapies for breast cancer, like the drug tamoxifen, target the disease's
 dependence on sex hormones. A team of German researchers speculated that PhIP
 induces breast cancer in laboratory animals in part because it has some interaction with
 sex hormone mechanisms in the body. They investigated this theory in laboratory studies
 using human cell lines.

 Through a series of in vitro tests, researchers discovered that, like steel to a magnet,
 PhIP is attracted to human estrogen receptors. When PhIP beats estradiol to a target
 receptor, it homesteads there, replacing the human hormone and disrupting natural
 interactions. In human breast cancer cells, PhIP also showed estrogen-like activity that
 increased with increasing doses of the substance.

 Estrogenic activity was measured as bioluminescence -- the light emitted by living cells
 during oxidation of a substance called luciferin in the presence of luciferase, a
 heat-sensitive enzyme. According to these measurements, PhIP's estrogen-like activity
 was 100,000 times lower than that of estradiol.

 "We believe that the levels produced of PhIP ingested with fried meat are so small that the
 increased estrogenic effects are insignificant for humans," concluded Wolfgang Pfau,
 Ph.D., of the Fraunhofer Society's Institute of Toxicology and Environmental Medicine in
 Hamburg, Germany.

 In laboratory conditions, PhIP, a heterocyclic amino compound produced when meat is
 cooked at high temperatures, causes several kinds of DNA damage -- mutations, strand
 breaks, and cell transformations. To address PhIP's documented potential harm, Dr. Pfau
 recommends a balanced approach of avoiding excessive consumption of fried or grilled
 meat as well as overcooked meat, while also making sure not to undercook meat to avoid
 the risk of food poisoning.

 In future studies, the German group plans to investigate why the breast is the target organ
 for PhIP as a carcinogenic agent, and whether this compound and its derivatives have an
 affinity to receptors for androgen, a male sex hormone, since PhIP also induces prostate
 cancer in male rats.

 Flame-Broiled Meat and Common Genotype Linked to Elevated Risk

 Researchers at Johns Hopkins University in Baltimore found that in women who had gene
 types associated with HCAs and other synergistic compounds, eating flame-broiled meat
 markedly increased the risk of breast cancer. Enzymes called N-acetyltransferases
 (NAT2) are part of the complex ignition sequence that activates HCAs. Approximately
 45 percent of all people also have a gene form called an allele that speeds up the rate at
 which carcinogens are activated or metabolized by the body. Like a bomb squad
 disarming an explosive, glutathione S-transferases (GST) may help neutralize these
 carcinogens.

 The data from this study showed that breast cancer risk increased for women who ate
 flame-broiled meat more than twice a month. The risk of breast cancer was concentrated
 among the women who had the fast-acting NAT2 profile. Women who had lower activity
 levels of GST and who consumed flame-broiled meat also had higher risk of breast
 cancer than women with higher GST activity profiles.

 After data were adjusted for smoking and other breast cancer risk factors, the connection
 with the genotypes remained. Flame-broiled meat was the common factor for elevated
 risk, and the association increased with quantity consumed.

 "These are very preliminary findings, which are part of a larger body of research that is
 examining the interactions of genes and environment," explained Kala Visvanathan, M.D.,
 a research fellow at Johns Hopkins School of Public Health in Baltimore, MD. "In time,
 this knowledge may help people better understand their risks and make informed dietary
 choices."

 This study is based on data collected in 1995 from 88 with breast cancer compared to 92
 control subjects from the University's large, prospective Washington County Study, which
 began in 1989. The two groups of women were matched for age, menopausal status, and
 other risk factors, and genetic profiles were assessed.

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