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Update: Over 25,000 Enrolled in Sister Study on Breast Cancer (dateline April 23, 2006)

Over 25,000 women have now enrolled to participate in the Sister Study, according to the study's website. The Sister Study, sponsored by the National Institute of Environmental Health Sciences, is the first study of its kind to investigate how the environment and genes affect a woman's chances of developing breast cancer. Researchers hope to enroll a total of 50,000 sisters of women who have been diagnosed with breast cancer.

By studying women who have similar genes and often share similar environments, researchers hope to gain insight into the causes of breast cancer. Women who meet the following requirements may be eligible to enroll in the Sister Study:

  • Be between 35 and 74 years of age
  • Live in the United States
  • Have no personal history of breast cancer
  • Have a sister (living or deceased) who has had breast cancer

According to the Sister Study website, "through a range of questionnaires and samples from the participants, the 10-year study will take a detailed look at how women's genes, and things women come in contact with at home, at work, and in the community may influence breast cancer risk."

Researchers are especially encouraging African-American, Latina, Native American, and Asian women, as well as women 60 and older, to join the Sister Study to ensure a diverse study sample and far-reaching results.

Women who enroll in the Sister Study will be mailed a study kit that contains study information, questionnaires, and material to use when collecting urine, toenail, and household dust samples. In addition, women will be required to participate in a visit by a female health professional during which time a blood test and other various tests will be administered. Paper questionnaires and a telephone interview are also required.

"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 learning what causes this disease," said Dale Sandler, Ph.D., Chief of the Epidemiology Branch at NIEHS and principal investigator of the Sister Study, in an NIH press release. "That is why joining the Sister Study is so important."

Additional Resources and References

  • To volunteer or learn more about the Sister Study, please visit or call 1.877.4SISTER (1.877.474.7837). Deaf/Hard of Hearing call 1.866.TTY.4SIS (1.866.889.4747)