Researching Environmental Causes of Cancer
Sen. Lincoln Chafee (R-R.I.) has just introduced legislation that would establish eight new research centers to study the link between breast cancer and the environment. Chafee's bill would provide $30 million per year for the next five years to the National Institute of Environmental Health Sciences to fund the projects.
"These [environmental] factors have largely been ignored," Chafee said as he proposed the Breast Cancer and Environmental Research Act. "Once these are determined, we might one day be able to provide women with information about what environmental factors they should avoid."
Over the past two decades there have been literally thousands of studies searching for specific links between breast (and other) cancers and a multitude of environmental factors: power lines, polluted water, pesticides, etc. Speculation has become especially rife since certain states have identified "cancer clusters" in which a disproportionate number of people have developed cancer.
Two states in particular-New York and Massachusetts-have been especially proactive. In 1998, New York launched the New York State Cancer Surveillance Improvement Initiative that has tracked the incidence of various types of cancer by zip code. The goal of the project is to use this data as a starting point for evaluating specific environmental risk factors that may be causing these elevated incidences.
Similarly, the Cape Cod Breast Cancer and Environment Study in Massachusetts is searching for reasons that Cape Cod has a 20 percent higher incidence of breast cancer than the rest of the state. Furthermore, certain areas within Cape Cod itself have particularly high incidences. Researchers from the Silent Spring Institute have now begun a second phase of the project to see what individual environmental factors may be playing a more active role.
Unfortunately, direct associations between specific environmental factors and such cancer clusters have been maddeningly inconclusive.
For example, scientists from the National Cancer Institute and the National Institute of Environmental Health Sciences have just finished an evaluation of five separate studies that specifically looked for a link between breast cancer and the use of two chemicals: the pesticide DDT and industrial PCBs. Both compounds are environmental chemicals that have similarities to estrogen, the so-called female hormone associated with a risk of breast cancer.
The women in the five studies totaled 1,400 breast cancer patients and 1,642 controls. Two of the studies were conducted among women in New York State, one was in Connecticut, and one was in Maryland. Half the women in the fifth study, the nationwide Nurses Health Study, live in northeastern states, including Maryland.
Writing in the May 16th issue of the Journal of the National Cancer Institute, the researchers noted that no definitive association between either DDT or PCBs and the Northeast's elevated rates of breast cancer could be confirmed.
"We found that the combined results from these five studies do not support an association between plasma or serum concentrations of DDE and PCBs and an increased risk of breast cancer," said the principal author, Francine Laden, Sc.D. of Brigham and Women's Hospital in Boston.
In each of the studies, blood was drawn from patients and controls alike and tested for DDE, the major breakdown product of DDT, and for PCBs. DDT and PCBs were widely used in the United States until the 1970s. They accumulate in the body's fatty tissues and thus can be found in human blood and breast milk many years after exposures.
SOURCES:
Press conference by Sen. Lincoln Chafee announcing the Breast Cancer and Environmental Research Act, May 9, 2001, Washington, DC
Journal of the National Cancer Institute, May 16, 2001; 93:731
National Institute of Environmental Health Sciences (http://www.niehs.nih.gov)
New York State Cancer Surveillance Improvement Initiative (http://www.health.state.ny.us)
Cape Cod Breast Cancer and Environment Study, Silent Spring Institute (http://www.silentspring.org)
[Table of Contents] [Archived Issues / Search] [The Breast Center]