Dietary Cadmium, Breast Cancer Link?
Highest Exposure Levels Linked to 21% Increased Risk, but More Study Needed, Researchers Say
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Cadmium and Breast Cancer Risk: Study Details continued...
Most (1,625) were cancers known as estrogen-receptor positive. These cancers require estrogen to grow.
The researchers divided the women into three groups, from lowest to highest dietary intakes of cadmium.
The lowest group took in less than 13 micrograms a day. The middle group took in about 13 to 16. The highest group took in more than 16 micrograms a day.
Experts recommend different ''safe'' levels. For instance, the World Health Organization recommends 25 micrograms per kilogram of body weight per month. For a 120-pound woman, that would mean about 45 micrograms a day.
The risk was higher in normal weight or lean women than in overweight women, the researchers found. While the overall risk from high cadmium levels was 21%, it was 27% for the normal weight and lean women.
The link between cadmium and breast cancer risk was stronger, not surprisingly, for estrogen-receptor positive cancer. Estrogen-receptor positive or ER-positive cancers are fueled by estrogen. The link between cadmium and breast cancer risk for ER-negative cancers was too slight to be significant from a statistical point of view.
Vegetables, Whole Grains May Offset Risk
Women who ate diets high in whole grains and vegetables appeared to be protected, Julin found.
It's not certain why. It could be due to the antioxidant properties of the foods, the researchers say.
The study was funded by the Swedish Cancer Society, the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, and the Swedish Research Council/Research Infrastructures.
Cadmium and Breast Cancer Risk: Perspective
"This is a very solid study that is likely to be influential in getting cadmium classified as either a breast carcinogen or a breast tumor promoter," says Kenneth Portier, PhD, managing director of the Statistics & Evaluation Center for the American Cancer Society.
He reviewed the findings for WebMD.
The new study ties in what researchers know about cadmium exposure from laboratory and animal studies and extends it to its effect in women, he says.
Exactly why cadmium is linked to risk is not clear. Portier suspects it is the estrogen-like properties of the cadmium. "Recent research has demonstrated that cadmium can operate like estrogen in the body, and we know from other data that estrogen promotes cancer growth."