- The Washington Times - Monday, October 18, 2004

A new national clinical trial will probe genetic and environmental causes of breast cancer by studying 50,000 sisters of women already diagnosed with the disease that is the second-leading cancer killer of women.

The Sister Study, conducted by the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health, is the largest trial of its kind and could easily cost $150 million over its 10-year duration.

“This is the most expensive study I’ve ever been involved in. But we knew if we were ever going to get solid information, we had to do it right. We had to collect a lot of information,” Dr. Dale Sandler, principal investigator in the study and chief of NIEHS’ epidemiology branch, said in an interview.

She said the Sister Study is the first research to examine breast cancer risk in siblings that will look not only at genes but environmental factors. “There is quite a lot of evidence that environment plays a part,” Dr. Sandler said.

For example, she said, variations in breast cancer risk have been seen in different parts of the country. Regions such as the San Francisco Bay Area in California and parts of Long Island, N.Y., and Massachusetts seem to have a higher-than-normal risk, although it is not known why.



“By studying sisters who share the same genes, often had similar experiences and environments, and are at twice the risk of developing breast cancer, we have a better chance of understanding what causes this disease,” she added.

While it’s clear some women have a family history of breast cancer, Dr. Sandler said, “Most women do not. … [G]enes are important, but they don’t explain it all. The truth is, only half of breast cancer cases can be attributed to known causes.”

About 5,000 sisters have already volunteered for the long-term study as a result of pilot projects under way in eight states, including Virginia. As of yesterday, the search for another 45,000 qualified women between the ages of 35 and 74 went national, Dr. Sandler said.

At the start, volunteers will complete several questionnaires and will provide a sample of their blood, urine, toenails and household dust. Dust, she said, offers a “snapshot” of chemicals found in a woman’s home when she joins a study. Toenails, blood and urine can also be used to measure exposure to chemicals at home or at work.

The American Cancer Society says nearly 216,000 U.S. women will be diagnosed with breast cancer this year. At least 40,100 U.S. women will die of the disease this year, according to the federal Centers for Disease Control and Prevention. Breast cancer ranks second behind lung cancer as the deadliest cancer in women.

To volunteer, visit the Web site at www.sisterstudy.org, or call toll-free 877/4SISTER. Women whose sisters survived breast cancer, as well as those whose sisters died of the disease, are welcome.

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