Are Environmental Toxins Causing Breast Cancer?

More emphasis must be placed on environmental factors in the fight against breast cancer, says a Tufts medical expert.

San Francisco [10-28-02] In the 1940s, a woman's lifetime risk of breast cancer was 1 in 22. Today, the risk has risen to 1 in 8. The swift increase, says Tufts scientist Ana Soto M.D., cannot be attributed to just genetics -- long believed to be the largest factor in whether women develop breast cancer. It's time to examine our environment for causes of this deadly disease, says the Tufts expert.

"This increase [in breast cancer] can't be attributed totally to genetic causation, and yet genetic causes remain the focus of most research," Soto -- a breast cancer researcher at Tufts' School of Medicine -- told Reuters. "I believe it is high time to seriously consider environmental chemicals as the most likely cause of this sudden increase in risk."

Soto - who has researched cell proliferation and breast cancer for more than 2 decades -- was one of several experts to testify at an informational hearing on breast cancer and the environment, jointly sponsored by the Senate Health and Human Services Committee and Assembly Health Committee in California. Currently the state is facing the highest incidence of breast cancer in the nation, and is looking into the possibility of chemicals in the air, water, food, and soil causing the problem.

Many experts, including Soto, say environmental toxins are likely to be responsible.

"While many breast cancer studies focus on genetics, or lifestyle factors such as reproductive history, alcohol use and exercise, Soto said there was little being done to assess how environmental toxins may be causing cancer," reported ABC News.

According to the Tufts professor of cell, molecular, and developmental biology, there is already some evidence to suggest a link.

"The increasing risk of breast cancer and other cancers has paralleled the proliferation of synthetic chemicals since World War II," said Soto. The Tufts professor added that only 7 percent of the estimated 85,000 chemicals registered for use in the United States have been reviewed for toxicity.

Soto first began investigating the health effects of environmental chemicals in 1989, when she and her research partner - Tufts professor Carlos Sonnenschein - made an accidental discovery. The Tufts scientists found that some laboratory plastics emitted chemicals that mimicked a female hormone -- causing breast cells to proliferate, which can lead to cancer.

Since then, Soto has dedicated her research to tracking the health impact - including the development of breast cancer -- associated with chemicals in the environment that imitate estrogen.

It's an area of study other experts believe to be important.

"We know that lifetime exposure to estrogen is a risk factor," Sheldon Krimsky -- a Tufts environmental health hazards expert -- told The Washington Post. "So it is logical that if we have chemicals that are creating more estrogen, the risk may go up."

Soto's research is beginning to have a major impact.

In light of her and other scientist's suggestions, officials in California's Bay area - where a woman's risk of developing breast cancer is 1-in-7 - plan to institute a new study to determine if environmental toxins are to blame: monitoring breast milk.

"Breast milk is regarded as a good 'biomarker' for exposure to toxins because chemicals can accumulate in the breast's fatty tissue for a number of years," reported Reuters.

By monitoring breast milk for toxins, scientists hope to track what sorts of chemicals are entering women's bodies.

"Due to the vast number of chemicals in the environment, linking them to breast cancer is going to be daunting," Soto told The San Francisco Chronicle. However, "searching for environmental agents may produce evidence that can be used to prevent cancer."