Environment and Breast Cancer: Science Review

Families and friends of women touched by breast cancer are calling for increased attention to research into the environmental causes - any factors that are not hereditary. The goal is to find causes of breast cancer that can be reduced or eliminated to prevent the disease.

To build an evidence-based strategy for preventing breast cancer, Susan G. Komen for the Cure invited Silent Spring Institute and their partners at Harvard University, Roswell Park Cancer Institute, and the University of Southern California to assess the scientific evidence on environmental causes. In the first year, the team reviewed areas of emerging research that promise to reveal new opportunities for risk reduction:

  environmental pollutants
  dietary factors
  body size and shape
  physical activity
  interactions of these factors with inherited genes

What is Cancer?

Cancer is the uncontrolled spread and growth of abnormal cells.

Some people are born with abnormal cells. Sometimes, changes in cells happen later. Cancer can start anywhere in the body and is affected by a variety of things that go on for a long time both inside and outside our bodies.

The cornerstone of the LIBCSP is the Breast Cancer and the Environment on Long Island Study, which was undertaken to determine whether certain environmental contaminants increase risk of breast cancer among women on Long Island. This investigation has been led by Dr. Marilie Gammon, of the University of North Carolina (UNC) at Chapel Hill, and has been a collaborative effort of New York City and Long Island researchers.

The primary aims were to determine if organochlorine pesticides, including DDT, polychlorinated biphenyls (PCBs), dieldrin, and chlordane, and polycyclic aromatic hydrocarbons (PAH), a ubiquitous pollutant caused by incomplete combustion of various chemicals including diesel fuel and cigarette smoke, are associated with risk for breast cancer among women on Long Island.

Dr. Gammon and colleagues reported the major findings from the study in August 2002. They found that organochlorine compounds are not associated with the elevated rates of breast cancer on Long Island. However, the researchers said that it is possible that breast cancer risk in some individuals may be associated with organochlorine exposures because of individual differences in metabolism and ability to repair DNA damage, and they are continuing to investigate these possibilities. The researchers also found that exposure to PAHs was associated with a modest increased risk for breast cancer.

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Marilie D. Gammon, Ph.D., principal investigator
Universtiy of North Carolina at Chapel Hill
Chapel Hill, N.C.

Is There a Connection Between Breast Cancer Risk and Environment?

Because established risk factors for breast cancer account for less than half of all cases, scientists believe environment may play a role in this disease.

It is possible that early exposure to some environmental factors increases the risk for breast cancer later in life. Environment means everything except inherited factors, including:

  Exposure to chemicals
  Diet and lifestyle choices

What Are Risk Factors

Risk factors either increase or decrease the chance of getting cancer. Risk factors are not necessarily things that cause cancer.

A factor that is associated with cancer in one person may not be associated in another. Having one or more risk factors does not mean that you will get cancer. Even though some of the risk factors for breast cancer are identified, no one factor ever explains any given case of breast cancer.

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Cornell University

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