Red Meat May Boost Breast Cancer Risk

Growth hormones, natural carcinogens in meat could be to blame, researchers say

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By Steven Reinberg
HealthDay Reporter

MONDAY, Nov. 13, 2006 (HealthDay News) -- Steaks, hamburgers and other red meat could raise younger women's risk for an estrogen-linked form of breast cancer, researchers report.

"Hormone receptor-positive" breast cancers are stimulated by higher levels of estrogen or progesterone circulating in the body. A majority of breast cancers fall into this category.

"We found that higher red meat intake may be a risk factor for hormone receptor-positive breast cancer among premenopausal women," said lead author Eunyoung Cho, an assistant professor of medicine at Harvard Medical School. "The majority of breast cancer is hormone receptor-positive, and the incidence of hormone receptor-positive tumors has been increasing in the United States," she added.

Earlier studies have looked at the association between breast cancer and red meat but only among postmenopausal women and without distinguishing between types of breast cancer. The results of these studies are largely inconclusive, Cho's team noted.

The new report was published in the Nov. 13 issue of the journal Archives of Internal Medicine.

In the study, Cho's team collected data on 90,659 female nurses aged 26 to 46 taking part in the ongoing Nurses Health Study II. The women were followed from 1991 through 2003.

The researchers excluded postmenopausal women and women who had had cancer. During follow-up, 1,021 women developed breast cancer. Of these cases, 512 were hormone receptor-positive cancers.

Cho's group found that women who had one-and-a-half servings of red meat a day had nearly double the risk for hormone receptor-positive cancer compared with women who ate less than three servings of red meat per week.

The researchers speculated that the increased risk may be linked to carcinogens found in cooked or processed red meat, hormone treatments used to spur growth in cattle and the type of iron found in red meat.

"Prevention of other chronic diseases, including colon cancer, already provides a good reason for choosing a diet low in red meat," Cho said. "So, our findings provide another reason for women to reduce their red meat intake."

One expert believes more study is needed, however.

"This is the first study that has actually examined the association between breast cancer and the intake of red meat in premenopausal women by type of cancer," said Eugenia Calle, the managing director of analytic epidemiology at the American Cancer Society. "But it's just one study," she said.

These results need to be replicated in other studies "before we can believe this association is true," Calle said.

Other studies that have looked for a connection between red meat and breast cancer have not found a link, she noted. Although these studies didn't look specifically at receptor-positive breast cancer, this type of breast cancer makes up half of all cases. "If there was something going on in that group, one would think that you would see a hint of it," Calle said.

Despite these doubts, Calle agreed that there is an association between red meat and other cancers, such a colorectal cancer. So, she concurs with the American Cancer Society's dietary recommendations to shun red meat.

"We recommend that people limit their consumption of processed and red meat, and eat fruits and vegetables and unrefined grains," Calle said. "We recommend this diet for many reasons," she said. "Whether breast cancer will end up being one of those reasons -- I'm not sure at this point."

More information

There's more on breast cancer at the American Cancer Society.

SOURCES: Eunyoung Cho, Sc.D., assistant professor, medicine, Harvard Medical School, Boston; Eugenia Calle, Ph.D., managing director, analytic epidemiology, American Cancer Society, Atlanta; Nov. 13, 2006, Archives of Internal Medicine

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