Cadmium link to TNBC is weak; association stronger for hormone-positive breast cancers

Cadmium in agricultural crops, especially root crops, has been linked to hormone-positive breast cancer in post-menopausal women.  The link to hormone negative, such as triple negative breast cancer, however, was weak—not statistically significant, according to research published in Cancer Research, the publication of the  American Association for Cancer Research. 

First, this is only a link—researchers are not saying cadmium causes breast cancer.  Second, the link occurs with high levels of cadmium-- more than 16 micrograms a day. And, third, a diet rich in whole grains and vegetables  appeared to reduce the effects of cadmium.

The research looked at the effects on cadmium on post-menopausal women.  The fact that no significant association was found between estrogen-negative breast cancers and cadmium could be because estrogen-negative breast cancer is more likely to affect premenopausal women and, therefore, the number of women with TNBC and other hormone-negative breast cancers in this study was too small to show an effect.

The research, done at the Karolinska Institutet in Sweden, followed 55,987 women for more than 12 years. Researchers estimated the dietary cadmium exposure using a food frequency questionnaire. During the 12 years the women were observed, 2,112 were diagnosed with breast cancer, including 1,626 estrogen receptor-positive and 290 estrogen receptor-negative cases.

Researchers divided cadmium consumption into three groups:

• The lowest group consumed less than 13 micrograms a day.

• The middle group consumed about 13 to 16.

• The highest group consumed more than 16 micrograms a day.

Overall, a higher exposure to cadmium in the diet was linked to a 21 percent increase in breast cancer. Among lean and normal weight women, the increased risk was 27 percent.  Interestingly, the effect was lessened by being overweight—some comfort for those trying to drop those extra pounds.

"Because of a high accumulation in agricultural crops, the main sources of dietary cadmium are bread and other cereals, potatoes, root crops and vegetables," said Agneta Åkesson, Ph.D., associate professor at Karolinska Institutet in Sweden. "It's possible that this healthy diet to some extent can counteract the negative effect of cadmium, but our findings need to be confirmed with further studies. It is, however, important that the exposure to cadmium from all food is low."

Cadmium has estrogen-like properties, which is why it might be linked to estrogen-positive disease.

To be safe, opt for organic vegetables when you can afford them.  


NOTE:  Cadmium is a natural element that occurs in the soil at low concentrations, but high levels in plants can be due to contamination of farmland because of deposits from the atmosphere and use of fertilizers.