The National Institute of Environmental Health Sciences (NIEHS) Sister Study Examines Breast Cancer Risk Factors (dateline November 28, 2004) | Breast Health News | Imaginis - The Women's Health & Wellness Resource Network

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Sister Study Examines Breast Cancer Risk Factors (dateline November 28, 2004)

The National Institute of Environmental Health Sciences (NIEHS) is currently recruiting participants for its Sister Study, a study on breast cancer risk factors that involves 50,000 sisters of women 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.

The largest study of its kind to study breast cancer risk factors, the Sister Study will follow participants for 10 years. Women who develop breast cancer will be compared with those who do not. At the onset of the study, participants will be asked to complete several questionnaires and provide a sample of their blood, urine, toenails, and household dust.

According to the National Institutes of Health (NIH), "the Sister Study will take the most detailed look ever 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 will study a range of environmental exposures, from personal care and household products, to workplace and other common exposures."

Eligibility requirements for 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

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.

"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."

"Genes are important, but they don't explain it all," said Dr. Sandler. "The truth is that only half of breast cancer cases can be attributed to known factors." Other known risk factors for breast cancer include advancing age, early onset of menstruation (before age 12), late menopause (after age 50), having a first child after age 30, never having children, and long-term use of hormone replacement therapy.

The Sister Study is open for enrollment nationwide.

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)