NEW YORK (Reuters Health) - Premenopausal women who eat large amounts of red meat appear to have an increased risk of developing breast cancer with receptors that are positive for estrogen and progesterone, according to a report in the Archives of Internal Medicine.

The current study is not the first to look at the association between diet and breast cancer. However, most previous studies have not looked at the results by the presence or absence of estrogen and progesterone receptors. Breast cancer growth is stimulated by these two hormones. Most studies have also focused primarily on women who are middle-aged or older.

While rates of hormone receptor-negative breast cancers have remained fairly stable over the years, there has been an increase in hormone receptor-positive cases, lead author Dr. Eunyoung Cho, from Harvard Medical School in Boston, and colleagues note. This latter trend may relate to increased consumption of red meat, which may influence tumor growth via hormone receptors.

Cho's team analyzed data from 90,659 women, between 26 and 46 years of age, who participated in the Nurses' Health Study II. During 12 years of follow-up, 1,021 women developed invasive breast cancer.

As the amount of red meat in the diet increased, so did the risk of estrogen-positive and progesterone-positive breast cancers. By contrast, no association was seen between red meat and estrogen-negative or progesterone-negative cancers.

Women who had more than 1.5 servings of red meat per day were 97 percent more likely to develop estrogen-positive and progesterone-positive breast cancer than those who ate three or fewer servings per week. In terms of red meat types, hamburger, beef or pork as a main dish, and a variety of processed meats were associated with an elevated risk of such cancers.

"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 authors conclude.