Despite advances in medical research, the incidence of breast cancer among women has not decreased in recent years. In fact, over the past 30 years, global incidence and mortality have increased at annual rates of 3.1 and 1.8 percent, respectively. Breast cancer remains the most common cancer in women worldwide. In the United States, about 1 in 8 women will develop invasive breast cancer during her lifetime. And each year more than 40,000 women in the U.S. die from the disease.

The vast majority of breast cancers are not due to hereditary factors. For example, the high-risk inherited breast cancer genes—BRCA1 and BRCA2—account for an estimated 5 to 10 percent of cases, and 80 percent of U.S. women diagnosed are the first in their family to get the disease.

group of laboratory flasks with colored liquid inside

A growing body of research points to environmental chemicals as important contributing factors. More than 200 chemicals have been associated with mammary gland tumors in animal studies, and about half of these are chemicals that women are routinely exposed to in their everyday lives.

Environmental chemicals can influence breast cancer risk in multiple ways:

  • chemical carcinogens can damage DNA causing uncontrolled cell growth
  • chemicals can act as tumor promoters that make cells grow
  • chemicals can alter the mammary gland, leaving it more vulnerable to carcinogens

Despite laboratory studies suggesting that many chemicals in consumer products increase breast cancer risk through these different mechanisms, an understanding of how these chemicals increase risk is far from complete. Few studies have looked at the effects of common chemicals on women’s breast health and even fewer studies have looked at their influence during times of critical development, such as puberty.

The ELLA study aims to fill that important research gap by focusing on exposure during puberty to three different chemicals—PFOA, BBP, and zeranol. These chemicals, found in everyday consumer products, are endocrine disruptors that mimic or disrupt the body’s natural hormone system, thereby interfering with cell growth and development. The project’s scientists are tracking the effects from exposure to these chemicals on breast development both in young teenage girls and in animal experiments, representing an innovative approach to studying early environmental determinants on breast cancer risk.