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The Sister Study: Latest Study on Breast Cancer

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Breast Cancer related image Photo: Getty Images

The National Institute of Environmental Health Sciences is conducting research on environmental and familial risk factors for breast cancer. They have been working on two studies. The Sister Study has closed enrollment and the Two Sister Study is still on-going.

What is the Sister Study?

A group of 50,000 women who have sisters with breast cancer enrolled in this long-term study. The researchers examined environmental and familial risk factors.

The cancer-free sisters were recruited nationally through healthcare providers, breast cancer advocates, the internet, a network of trained recruitment volunteers and a national advertising campaign. The study followed these women for at least 10 years.

Information about genes, lifestyle and environmental risk factors that lead to breast cancer were gathered and will be analyzed. Enrollment in the Sister Study ended March 31, 2009. Study group participants whose sister was diagnosed with breast cancer before the age of 50, her sister who had breast cancer, and any living biological parents, may be invited to participate in the Two Sister Study.

What did the researchers hope to find?

It is thought that these sisters have about twice the risk of developing breast cancer than other women. The researchers speculated the frequency of relevant genes and shared risk factors would be greater among this population, thus increasing the statistical power of the study to detect risk factors.

What type of data was collected?

Immediately following enrollment in the study, participants agreed to have a fasting blood sample drawn. A female staff member of Examination Management Services visited each participant to collect the blood sample.

At this same time, the examiner measured height and weight, hip and waist circumference and blood pressure. A sample of the participant’s first urine of the day, toenail clippings and house dust were collected.

Each woman was asked to complete four questionnaires included in the Sister Study kit. Each participant completed a detailed telephone interview which was conducted in two parts.

Each year, the participants were asked to update the researchers of any change in address, phone number or health status. They were asked to complete a questionnaire or telephone interview every other year.

If participants were diagnosed with breast cancer, another type of cancer or a disease, such as heart disease, permission was requested to contact their health care provider for more information.

Additional biological samples were requested if a participant was diagnosed with breast cancer. Granting permission was voluntary.

Who led the research?

The principal investigator of the Sister Study was Dale Sandler, PhD., who is the Chief of the Epidemiology Branch at the National Institute of Environmental Health Sciences (NIEHS). Co-investigator was Clarice Weinberg, PhD., who is the Chief of the Biostatics branch at the NIEHS. Lead investigator was Lisa DeRoo. PhD., who is a staff scientist at the NIEHS.


American Cancer Society: What’s New in Breast Cancer Research and Treatment?
Sept. 9, 2011

National Institute of Environmental Health Sciences: The Sister Study, Sept. 9, 2011

National Institute of Environmental Health Sciences: Sister Study, Sept. 9, 2011

Reviewed September 12, 2011
by Michele Blacksberg R.N.
Edited by Jody Smith

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