A case for breast cancer prevention

by Sarah Dunagan, from the Silent Spring Institute

“How do we know the gunshot killed the victim?” asked Julia Brody, Executive Director of Silent Spring Institute, during her testimony to the President’s Cancer Panel. “The gun was raised and fired, the bullet entered a vital organ, and the victim fell to the ground.” But how do we know environmental factors contribute to breast cancer? In this case, it’s much harder to establish a clear cause and effect relationship.

Each year, the President’s Cancer Panel—a watchdog group of advisors charged with monitoring the National Cancer Program—holds a series of meetings to gather input from experts and the public on a particular theme. While in past meetings the panel has focused on topics such as lifestyle and treatment, this year they are focusing, for the first time ever, on environmental factors. The panel will present a report with its recommendations to President Obama later this year.

At the panel’s meeting on Air Pollution and Water Contamination, Brody advocated a new strategy for environmental health sleuthing. Taking the traditional “innocent until proven guilty” approach—which requires waiting for definitive proof that a given chemical causes breast cancer before taking action—hasn’t been working. This is because it can take many years after an exposure for breast cancer to develop, women are exposed to a toxic soup of chemicals, and it’s difficult to untangle the many interwoven genetic and environmental factors that can contribute to the disease.

With medical research, we can dispel some of this ambiguity by using clinical trials to test, for example, the safety of a given drug. But we can’t apply this model to study the effects of pollutants on women’s health because it would be unethical to test a toxic chemical on a group of women and wait to see if they get sick. So what, then, are we to do?

We don’t have to throw up our hands in the face of this challenge. Instead, we can work to build the case for a “better safe than sorry” approach that would rely on animal and cell studies that illustrate how chemicals can contribute to breast cancer, and studies showing humans are exposed to those same chemicals. Taken together, this evidence would create the foundation for preventive action to reduce our exposures to harmful chemicals.

“We see substantial evidence of links between environmental pollutants and breast cancer, enormous knowledge gaps that we can fill immediately, and opportunities for precautionary action,” said Brody. “If we take steps to protect ourselves and our children from chemicals that cause cancer, we will also see benefits for numerous other health endpoints, including diabetes, obesity, neurological disease, and infertility.”

To read the full text of Brody’s testimony, visit the Silent Spring Institute homepage.