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Study Shows Breast Cancer Risk Starts Early -- Really Early

WebMD Health News

Aug. 31, 2000 -- If you're a woman, the diet your mother ate while she was pregnant with you and the diet you ate as a child may have a bigger effect on her risk of breast cancer than what you eat during much of adulthood.

"At certain stages of a woman's life, particularly in the womb and after menopause, diets that induce high estrogen levels do indeed seem to increase her risk of getting breast cancer," lead researcher Leena Hilakivi-Clarke, MD, said at a press conference sponsored by the American Institute for Cancer Research. "During reproductive years, however, high estrogen levels show no effect."

The research suggests that the link between the female hormone estrogen and breast cancer risk is very complex -- even more than previously thought. In addition, their research demonstrates the important role played by the stage of life at which a woman was exposed to a particular diet.

On the other hand, high estrogen levels at other times of life, such as childhood, actually protect a woman from getting breast cancer, said Hilakivi-Clarke, who is research associate professor in the department of oncology at Georgetown University Medical School in Washington. Moreover, some studies have shown that certain traits associated with high estrogen levels during childhood, including high body mass and high-fat diets, were linked to a lower breast cancer risk. In the study, the researchers gave pregnant rats different diets -- some were designed to raise estrogen levels in the unborn rats.

These are surprising results, because most of the scientific literature to date suggests that high-fat diets tend to raise breast cancer risk, not lower it, she noted. However, she cautioned that the study of diet's links to cancer is still in its infancy and that dietary recommendations cannot be made based on these findings.

Joanne Dorgan, PhD, epidemiologist in the population science division at the Fox Chase Cancer Center in Philadelphia, agrees that it is too soon to draw definitive conclusions. "It's really too early to make recommendations in terms of pregnancy or how to feed your child," she says. "This definitely is an area that needs more work."

Hilakivi-Clark was quick to point out that the data are preliminary and said, "Even if it turns out that early diets exert the greatest influence on lifetime risk, the contributions of diet during adulthood are still considerable. Everything we know says that it is never too late to take dietary steps that provide real protection."

Although researchers have not identified specific dietary changes aimed at preventing breast cancer, there are some dietary and lifestyle changes everyone can make to decrease their overall cancer risk, says John D. Potter, MD, PhD, a member of the Cancer Prevention Research Program at the Fred Hutchinson Cancer Research Center in Seattle. "We most likely can lower our cancer risk by eating a diet rich in vegetables and fruit, maintaining a low weight, engaging in lots of physical activity, and watching our alcohol intake." There is less evidence about the role played by legumes, nuts, and whole grains in lowering cancer risk, he adds.


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