Heavy Diet of Red Meat May Boost Breast Cancer Risk

Here's news you may wish to pass along to some of your patients: Younger women who chow down on a hamburger for lunch and have red meat for supper on a regular basis may be at increased risk for some breast cancers, according to an article in the Nov. 13 issue of Archives of Internal Medicine.

"Higher red meat intake may be a risk factor" for estrogen and progesterone receptor-positive breast cancer among premenopausal women, says the abstract for the article, "Red Meat Intake and Risk of Breast Cancer Among Premenopausal Women." The study found no such association between red meat intake and estrogen and progesterone receptor-negative breast cancer.

"The incidence of hormone receptor-positive tumors has been increasing in the United States, especially among middle-aged women," say the study's authors, led by Eunyoung Cho, Sc.D., an assistant professor of medicine at Harvard Medical School, Boston, and associate epidemiologist at Brigham and Women's Hospital there.

The researchers explored data from the Nurses' Health Study II, which in part featured female registered nurses' reports of how often they ate each of more than 130 food items, including beef, lamb, pork, hamburger, bacon and hot dogs. In 1989, nurses ages 25 to 42 in 14 states completed an initial questionnaire about their medical history and lifestyle. Follow-up food frequency questionnaires were sent to the women in 1991, 1995 and 1999. The researchers analyzed reports from 90,659 nurses for the study and documented 1,021 cases of breast cancer among the subjects by 2003, including 512 cases of hormone receptor-positive cancer.

Nurses who ate more than 1.5 servings of red meat per day had almost twice the risk for hormone receptor-positive breast cancer as did the nurses who ate fewer than three servings of red meat per week. "That’s a pretty strong association" between consumption of red meat and risk for that type of cancer, said Cho in a Nov. 14 Washington Post article. The Post article mentioned earlier research that pointed to a possible connection between eating red meat and having an increased risk for colon cancer. "There are already other reasons to minimize red meat intake," Cho said in the Post article. "This (study) just may give women another good reason."

In the Archives study report, the authors note, "Epidemiologic studies examining hormonal risk factors and breast cancer by hormone receptor status have generally supported the hypothesis that receptor-positive tumors differ etiologically from receptor-negative tumors. Dietary factors may also have different effects on the risk of breast cancers characterized by hormone receptor status." They add, however, that they're unaware of specific studies evaluating red meat intake and breast cancer risk according to tumor hormone receptor status.

Even so, the authors suggest, "Several biological mechanisms may explain the positive association between red meat intake and hormone receptor-positive breast cancer risk," positing that meat intake may be hormonally mediated. They refer to other research citing cooked or processed red meat as a source of carcinogens that increase mammary tumors in animals and mention studies that associate overall breast cancer risk with the intake of heterocyclic amines created during the cooking of red meat. The authors add, "Exogenous hormone treatment of beef cattle for growth promotion, which is banned in European countries but not in the United States, has been of concern."

"Given that most of the risk factors for breast cancer are not easily modifiable, these findings have potential public health implications in preventing breast cancer and should be evaluated further," the study authors conclude.