By Tim Bonfield
The Cincinnati Enquirer

Starting this fall, Cincinnati researchers will participate in one of the nation's biggest efforts to determine what role environmental factors play in causing breast cancer.

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Chemicals and breast cancer At a forum Tuesday evening, Cincinnati researchers said the link between chemical exposures and breast cancer has not been well-studied through the years: • Of 2,800 commonly used chemicals (more than 1 million pounds a year emitted into the environment), a total of 44 have been shown to induce breast cancer in animals. • Not one of those 44 chemicals has been proven to cause breast cancer in humans. • Most studies have focused on one chemical at a time. • Most studies have not looked at how mixtures of chemicals might act in concert to cause cancer. • Most studies have not looked at how chemicals interact with genetic variations that might make some people more likely than others to be harmed by the exposure. Source: UC and Cincinnati Children's Hospital Medical Center Odds of developing breast cancer Figures show the chances of a woman developing breast cancer during various age groups By age 30: 1 in 2,212 By age 40: 1 in 235 By age 50: 1 in 54 By age 60: 1 in 23 By age 70: 1 in 14 By age 80: 1 in 10 Lifetime odds: 1 in 8 Source: National Cancer Institute

About 450 7- and 8-year-old girls will be invited to join a study called "Growing Up Female" that will track girls for seven years as they develop through puberty. Meanwhile, researchers in related projects will expose rats to a variety of chemicals that might play a role in triggering breast cancer.

The projects are part of a $35 million, four-city study to hunt down more of the long-unknown causes of a common type of cancer for women. The study is sponsored by the National Institute of Environmental Health Sciences.

More than 15,000 women are living with breast cancer in Greater Cincinnati, according to the Breast Cancer Alliance of Greater Cincinnati. The advocacy group was formed a decade ago to push for more research into the causes of breast cancer. It was among several groups that pushed for this study.

"Ten years later, we are finally seeing some research here in our own community," president Ann Hernick of the Breast Cancer Alliance said.

The local studies will be conducted by University of Cincinnati and Cincinnati Children's Hospital Medical Center. Girls will be recruited from a handful of school districts, which have not been named.

Other centers involved with other parts of the national project include Michigan State University, University of California-San Francisco and the Fox Chase Cancer Center in Philadelphia.

Nationwide, more than 212,000 people, including 1,300 men, are expected to develop breast cancer this year, according to the American Cancer Society. Meanwhile, more than 40,000 will die from the disease, making breast cancer the second-leading cause of cancer death for women, after lung cancer.

While some causes for breast cancer are known - such as having a family history of the disease or being exposed to radiation - most cases are not easily explained.

By gaining new understanding of what causes breast cancer, researchers hope to help more women avoid the disease and to come up with better treatments for those who do get sick.

The researchers want to learn how exposure to environmental factors - especially during puberty - interacts with genetic traits to make some women more likely than others to develop breast cancer, said Dr. Robert Bornschein, director of UC's department of environmental health.

Before and during puberty, participating girls will get repeated blood and urine tests and a series of body measurements. They also will be asked many questions about their diets, activity levels and stress factors in their lives.

The animal studies will look at several chemicals that could cause cancer directly, could promote tumor growth or could affect a woman's hormone levels in ways that could lead to breast cancer.

Chemicals to be studied include:

• Heavy metals such as lead and cadmium.

• Pesticides such as DDT or chlordane.

• Compounds often found in plastics such as alkyphenols and phthalates.

• Several phytoestrogens that can be found in food.

Many of these substances are known to cause cancer in rats. However, researchers stressed that none of the chemicals has been proven to cause breast cancer in women.

Researchers also stress that their concept of environmental exposure goes beyond possible links to pollution or man-made chemicals found in everyday products.

For example, researchers in Cincinnati will be tracking how dietary habits, exercise and obesity affect development during puberty.

Previous studies indicate that girls who develop breasts as their first sign of puberty are more likely to develop breast cancer later in life than girls who develop pubic hair as their first sign of puberty. One theory is obesity causes changes in body chemistry that increase breast cancer risk.

Likewise, researchers consider stress a possible environmental cause of breast cancer. High levels of stress - often related to family, relationship or job problems - also can affect body chemistry.

"It's very difficult to separate lifestyle factors and environmental factors," said Dr. Sue Heffelfinger, a researcher and co-administrator of the Cincinnati breast cancer study.

"Environmental exposure isn't just breathing the air near an industrial site. It also is about what we eat and drink. We eat carcinogens every day."

The big challenge will be pinning down which combinations of exposures and genetic factors pose the highest risk of developing breast cancer.

The study will run for seven years. Several progress reports are expected along the way.

E-mail tbonfield@enquirer.com