The More Red Meat Eaten, the Higher the Risk
Summary: Women who eat lots of red meat may be at greater risk of getting a certain type of breast cancer at a young age, a new analysis by Harvard researchers suggests.
Why it's important: Breast cancer is the most common cancer among women in the US, and finding ways to prevent it is a high priority. If the connection seen in this study holds true in further research, cutting back on red meat may prove to be a relatively simple way for women to lower their risk of some types of breast cancer.
What's already known: American Cancer Society nutrition guidelines already recommend limiting red meat because eating a lot of it is linked to colorectal cancer and prostate cancer. Red meat contains compounds that can turn into cancer-causing chemicals when cooked. Red meat also contains a lot of fat, which can cause weight gain -- and being too heavy is known to raise the risk of breast and other cancers. However, earlier studies looking at red meat consumption and breast cancer risk showed mixed results, and few included large numbers of younger women, whose breast cancer risk factors may differ from those of older women. Breast cancer is most common in women age 50 and older; about 78% of cases occur in this age group.
How this study was done: Harvard Medical School researchers wanted to tease out the possible relationship between red meat and breast cancer in younger women. To do so, they looked at the records of 91,000 women between the ages of 26 and 46 who were taking part in a large lifestyle study of women called the Nurses' Health Study II. During the course of the study, these women -- none of whom had reached menopause -- periodically answered questions about their diet, including how much red and processed meat (including beef, lamb, pork, hamburger, bacon, hot dogs, etc.) they ate and how often they ate it. The findings appear in the Archives of Internal Medicine.
What was found: Over the course of 12 years, 1,021 of the women in that group went on to develop invasive breast cancer. Women who ate lots of red meat -- more than 1.5 servings per day -- had nearly double the risk of developing breast cancer as did those who ate 3 servings a week or less. But this was only true for cancers that had receptors for the hormones estrogen and progesterone (ER+/PR+). Eating red meat did not appear to raise the risk of developing tumors that did not have those receptors (ER-/PR-). Hormone receptor positive cancers are more common than hormone-negative cancers, and easier to treat because they respond to drugs like tamoxifen and aromatase inhibitors.
The study did not examine how red meat might raise breast cancer risk.
The bottom line: More research is needed on how eating red meat might influence breast cancer risk, says lead researcher Eunyoung Cho, ScD, and colleagues. Other experts agree.
"While the study is well done, it is still just a single study," notes Jeanne Calle, PhD, managing director of analytic epidemiology at the American Cancer Society. "These results must be replicated in other studies before we can believe that this association is true."
Nevertheless, Calle says, American Cancer Society nutrition guidelines recommend eating less red meat and processed meat, which is also likely to have health benefits beyond reducing cancer risk.
Citation: "Red Meat Intake and Risk of Breast Cancer Among Premenopausal Women." Published in the Nov. 13, 2006 Archives of Internal Medicine (Vol. 166. No. 20: 2253-2259). First author: Eunyoung Cho, ScD, Brigham and Women's Hospital and Harvard Medical School.
