How can studying sisters help identify risk factors for breast cancer?

Studying sisters of women with breast cancer to uncover genetic and environmental causes of breast cancer


Breast cancer is the most common cancer in women, but many contributors to breast cancer risk are still unclear. The Sister Study, conducted by the National Institute of Environmental Health Sciences (NIEHS), was launched in 2003 to enroll 50,000 women who had a sister with breast cancer but who did not have breast cancer themselves.

Studying women with a family history can help to discover both genetic and non-genetic risk factors for breast cancer and other diseases.


Westat, under contract to Social and Scientific Systems, developed the web-based applications used to enroll study participants and a study management system to track and report on the progress of participants reaching their study milestones.

Under the same contract, Westat also supports the Sister Study in data management of extensive baseline and follow-up questionnaires, laboratory assays, and many other data sources. In addition, we provide analytic support to NIEHS-funded researchers by preparing study-specific datasets and unique variables, and by reviewing and replicating, including independent replication of study findings prior to journal publication.


Sister Study participants continue to complete health questionnaires every year. Research is ongoing on causes of breast cancer as well as quality of life and outcomes among breast cancer survivors. Research also focuses on other health issues and chronic conditions in addition to breast cancer.

The findings from this study provide a greater chance of identifying risk factors that may help find ways to prevent breast cancer.


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