The Sister Study is the only long-term, national study of women whose sister had breast cancer. The primary goal of the Study is to learn how genes and the environment affect the chances of getting breast cancer, although risk factors for other diseases will be studied as well. Recruitment began in 2004, with a target goal of 50,000 participants.

According to the official Sister Study website, they are close to reaching this mark. Therefore, they are now only enrolling women from certain subgroups that are under-represented.

Women from the following groups are still needed:

- African Americans, Latinas, Asians, and Pacific Islanders between the ages of 35 and 74

- Caucasians between the ages of 65 and 74

- All women between the ages of 35 and 74 with a high school degree or less

If you would like to participate but are not sure if you qualify, there is a questionnaire on the website (link below) to help you, or you can call the number given on the website and speak directly with a counselor.

One of the reasons that the Sister Study is so important is that it examines many factors – in great depth – at the same time. Not only does it measure possible inherited factors in breast cancer risk, it takes into account very detailed information about each woman's environment at home, at work and in her community. Thus, the data collected will allow researchers to study countless combinations of factors: age, race, geographic region, etc.

The Study will follow 50,000 women, ages 35 to 74, in the United States and Puerto Rico, whose sisters had breast cancer, and will run for at least ten years. Researchers believe that the Study will give them valuable information as to why women get breast cancer, leading to definitive prevention strategies. Additionally, the Sister Study will examine risk factors for many other diseases, such as coronary heart disease, osteoporosis and some other types of cancer.

Who can join the Study?

If you meet the criteria for under-represented subgroups listed above, you can join if your blood sister had breast cancer, you have never had breast cancer, you are between the ages of 35 and 74, and you live in the United States or Puerto Rico.

Why study sisters?

Research indicates that sisters of women with breast cancer have about twice the risk of developing breast cancer themselves, compared to women who do not have a first-degree relative with breast cancer. Supporting the theory that sisters share many of the same risk factors for developing breast cancer, researchers hope to define these risk factors with much greater accuracy than other types of studies might provide.

What will the Study cost me, in terms of time and money?

There is no financial cost to participate in the Study. Enrolling in the program takes about 15 minutes. There are then two telephone interviews, which take about one hour each, and a home visit which takes between 30 and 45 minutes. Lastly, a questionnaire and lab tests are completed. All in all, your time investment in the first year will be about five hours. From that point on, there will be a yearly telephone interview which will take about 15 minutes, and a follow-up interview every two years that will take about 30 minutes.

If I have breast cancer, can I enroll my sister(s)?

No. Enrollment is voluntary, which means your sister would have to enroll herself. In other words, you can't ask the Sister Study to contact your sister and ask her to enroll. Your sister would have to contact the Study directly to enroll.

Why can't women who've already had breast cancer enroll?

Once you've had breast cancer, it is too late to collect some of the information the Study requires. Additionally, you may have made lifestyle changes due to your cancer which could affect the results.

What about privacy issues?

There are several protections in place to protect the privacy of the participants. Among other things, participants are identified by number only--name and contact information is kept completely separate and can only be accessed by certified staff. Additionally, the Sister Study has received a Certificate of Confidentiality from the Department of Health and Human Services. Certificates of Confidentiality are authorized by law under the Public Health Services Act (42 U.S.C. section 241(d)). The Certificate protects the research data collected from compulsory legal demands such as court orders or subpoenas. Under the Certificate, researchers cannot be forced by anyone to disclose information which could in any way identify participants.

The Sister Study is coordinated and run by the National Institute of Environmental Health Sciences (NIEHS). The NIEHS is one of the National Institutes of Health, and is a division of the Department of Health and Human Services. For more information, click on the links below.