Researchers at Brigham and Women's Hospital (BWH), in which Dr. Cho led the investigation, studied the association between red meat intake and breast cancer in 90,659 women from 1991 through 2003 (when they had an average age of 36). It was required that these women in premenopause
and had not previously had cancer to be included in this analysis. The participants filled out food questionnaires in three opportunities: 1991, 1995 and 1999 in order to give information about their diets and beverages daily routines, and whether or not they developed breast cancer during that period.
"The overall risk of breast cancer in premenopause
is low when we compared to getting the disease after the menopause. So even at the highest rates of meat consumption, this is overall still a relatively small increase," says Henry Scowcroft at Cancer Research UK.
One of the hypotheses might be because women are consuming more foods that contain added hormones or hormone-like compounds than they used to in previous decades, Dr. Cho says.
The hormones or hormone-like compounds in red meat may develop the growth of hormone-sensitive breast cancer by attaching to specific hormone receptors on the tumors, Cho suggests.
On the other hand, researchers said the findings provide another motivation to limit consumption of red meat, which is already known to raise the risk of colon cancer.
"So many risk factors for breast cancer are things that you can't alter" said Nancy E. Davidson, a breast cancer expert at Johns Hopkins University in Baltimore. "This represents something women could take charge of, something you can change to diminish your risk."