October 2023 Featured Interview
Sisters Share Special Secrets:
Marking the 20th Anniversary of the Sister Study
Interview with
Dale Sandler, Ph.D. & Katie O'Brien, Ph.D.
Scientists with NIEHS' Sister Study
Photo Courtesy: Sister Study
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Photo Courtesy: Sister Study
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This October marks the 20th anniversary of the Sister Study, the nation’s largest and longest study of women with a close family history of breast cancer that seeks to identify the environmental and genetic factors affecting a woman’s chance of developing breast cancer. The study is led by the National Institute of Environmental Health Sciences (NIEHS), part of NIH.
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To commemorate this 20-year milestone and to mark National Breast Cancer Awareness Month, NIEHS developed a suite of products including a 10-minute video available in English, which is also available with Spanish captions, to showcase how the Sister Study started, what it has accomplished, and to spotlight the participants who make it all possible. All the materials are available on the Sister Study website starting this month.
Although the study isn’t recruiting any more participants, current participants are encouraged to stay engaged and respond to periodic questionnaires. (Full disclosure: I have been part of the study since its inception. My sister, a survivor, once gave me a ceramic trivet that says, “Sisters Share Special Secrets.” In joining the study, it was my hope that some of those secrets could be uncovered and put to good use.) |
Carol's Trivet, A Gift from her Sister
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In conjunction with the study’s milestone anniversary, I interviewed Dr. Dale Sandler (a conceiver and principal investigator for the study) and Dr. Katie O’Brien (a staff scientist at NIEHS who helps lead the study).
Who conceived of the Sister Study?
Dr. Sandler: A small group of epidemiologists at the National Institute of Environmental Health Sciences, part of NIH, designed the study. The team, led by Dr. Clarice Weinberg and me, was invited to come up with a new way to study the impact of the environment on breast cancer incidence. People were concerned about the rising rates of breast cancer and were wondering if they were connected to things in the environment.
We designed a study that focused on women with a sister with breast cancer since they were known to be at increased risk. Some part of this increased risk is due to shared genes. But sisters likely share similar lifestyles and environments, including experiences and exposures that might be breast cancer risk factors. As a bonus, we thought women whose sisters [had been diagnosed with] breast cancer would potentially be more motivated to be part of a long-term study.
Why is the Sister Study important?
Dr. Sandler: The Sister Study is important because it looks at lifestyle and environmental exposures across the life-course, as well as genetic and biological factors that may affect a woman’s chance of developing breast cancer. It helps us learn about ways we can prevent breast cancer.
Who conceived of the Sister Study?
Dr. Sandler: A small group of epidemiologists at the National Institute of Environmental Health Sciences, part of NIH, designed the study. The team, led by Dr. Clarice Weinberg and me, was invited to come up with a new way to study the impact of the environment on breast cancer incidence. People were concerned about the rising rates of breast cancer and were wondering if they were connected to things in the environment.
We designed a study that focused on women with a sister with breast cancer since they were known to be at increased risk. Some part of this increased risk is due to shared genes. But sisters likely share similar lifestyles and environments, including experiences and exposures that might be breast cancer risk factors. As a bonus, we thought women whose sisters [had been diagnosed with] breast cancer would potentially be more motivated to be part of a long-term study.
Why is the Sister Study important?
Dr. Sandler: The Sister Study is important because it looks at lifestyle and environmental exposures across the life-course, as well as genetic and biological factors that may affect a woman’s chance of developing breast cancer. It helps us learn about ways we can prevent breast cancer.
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How many women have participated over the years?
Dr. Sandler: A total of 50,884 sisters of women with breast cancer from the U.S., including Puerto Rico, enrolled in the study. Most have continued to participate up to today. How did you recruit them? Dr. Sandler: NIEHS launched a national campaign in 2003. This included using the media and other outreach strategies to reach the diverse group of women that we wanted to include. We worked with breast cancer advocacy and support groups, women’s sororities, medical groups, media personalities and [others] that helped spread the word about the study. We also used direct mail, television and radio appearances, and direct outreach at conventions and medical conferences to doctors’ offices and more. In some cases, women who joined the study also helped us spread the word about the study through outreach to friends, neighbors, and community groups. |
Sister Study Participants Come from all 50 States and Puerto Rico
Click Graphic for More Information |
What results has it yielded to date?
Dr. Sandler: The study has researched many factors that may contribute to a woman’s chances of developing breast cancer or other health conditions, including air pollution; proximity to industrial emissions; neighborhood characteristics; sleep patterns; light at night; early life trauma; psychosocial stress; dietary factors; permanent hair dyes, chemical hair straighteners and some other personal care products; and obesity. The study has also explored genetic factors related to breast cancer, including how exposure-related changes to DNA may influence biological aging and breast cancer risk.
A full listing of the research publications from the Sister Study, which so far includes about 300 articles, is available.
Did any of the results surprise you? If so, how? If not, why not?
Dr. Sandler: The study has researched many factors that may contribute to a woman’s chances of developing breast cancer or other health conditions, including air pollution; proximity to industrial emissions; neighborhood characteristics; sleep patterns; light at night; early life trauma; psychosocial stress; dietary factors; permanent hair dyes, chemical hair straighteners and some other personal care products; and obesity. The study has also explored genetic factors related to breast cancer, including how exposure-related changes to DNA may influence biological aging and breast cancer risk.
A full listing of the research publications from the Sister Study, which so far includes about 300 articles, is available.
Did any of the results surprise you? If so, how? If not, why not?
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"We’ve been most surprised by our studies on personal care product use, especially the use of chemical straighteners, which we have now shown may be linked to breast and uterine cancer. The women in our study use a lot of different products, and we think it’s important to understand how they may impact health." ~ Dale Sandler, Ph.D. |
Dr. Sandler: We’ve been most surprised by our studies on personal care product use, especially the use of chemical straighteners, which we have now shown may be linked to breast and uterine cancer. The women in our study use a lot of different products, and we think it’s important to understand how they may impact health.
One of the study’s original goals was to study how early life social, behavioral, and environmental factors may impact later health. Few other cohorts have included questions about early life, so it’s been fascinating to learn more about [the importance of] in utero, childhood, and adolescent environments. |
Has the focus of the questions you ask participants changed over the years in response to what you’ve learned?
Dr. Sandler: Yes. For example, as climate and weather-related disasters continue to increase, we’ve linked information from outside data sources to participant residence histories about climate factors, such as heat waves and other disasters, and plan to ask questions about how participants cope and about access to and use of air conditioners and air filters. As we’ve learned how important the social and neighborhood environment can be in shaping exposures and access to medical care and needed services, we’ve been increasingly adding information about the places where study participants live.
During the pandemic, we added questions about COVID infection and about how the pandemic was changing people’s routines, access to care, and psychological stress – all things that could have implications for health down the road. We also continually add questions or ask for more details about certain topics if we discover something interesting and want to dig deeper. One example is the addition of more detailed questions about hair texture and hair product use across the life-course.
What implications will the work have going forward?
Dr. Sandler: We plan to continue the study for many years to come and address issues of relevance to the participants. Breast cancer will continue to be our main focus, but we’ll also keep studying other cancers and chronic diseases, especially those more relevant to an aging population. All the information that we have collected can be important for uncovering causes of other conditions, and we’re partnering with researchers who bring specialized expertise to help us make full use of this data. For example, we’re working with university collaborators to study Parkinson’s disease and diverticulitis.
How did you find your way to the Sister Study?
Dr. Sandler: I was an epidemiologist who studied environmental risk factors for chronic diseases and was intrigued by the public’s call for a study of how changes in the environment could be impacting breast cancer risk. I was part of the team that came up with the original idea for the study and designed the cohort, and I continue to lead it as the study’s Principal Investigator.
Dr. O’Brien: I started working on the Sister Study as a post-doctoral fellow in 2013, a few years after enrollment had completed. I was interested in how social, behavioral, and environmental factors were related to breast cancer, especially breast cancer in young women and racially – or ethnically – minoritized groups. I now serve as Staff Scientist for the study, which means I help facilitate many of our ongoing research projects – everything from designing questionnaires to mentoring young researchers to collaborating with researchers across the globe.
What does this work mean to you?
Dr. Sandler: The Sister Study researchers are passionate about learning more about breast cancer so we can help lower the burden of disease for future generations. We hope the knowledge gained from our research will help guide decision-making at the individual, clinical, and policy levels. In addition, the scope of the study has provided an opportunity to bring in early career researchers who have used the data to ask important new questions. It’s especially exciting to be motivating the next generation of scientists who will continue to study the many factors that contribute to breast cancer.
Anything else you feel is important to say about the study or your work there that we haven’t touched on?
Dr. O’Brien: An important part of the study that should not be overlooked is the dedication of the study participants who have been especially committed to this effort over the years. So many of those who enrolled continue to respond enthusiastically to our requests for updates. Some keep up with what we’re learning by actively following our Facebook posts. And others reach out to us from time to time with questions or suggestions for how we can do even better. It’s great to be part of a study that is meaningful to both the research team and the study participants.
Where do you find sanctuary?
Dr. Sandler: I love being on or near the water and try to spend as much time as possible at the beach on the North Carolina coast.
Dr. O’Brien: I like going on long walks with my dog.
Dr. Sandler: Yes. For example, as climate and weather-related disasters continue to increase, we’ve linked information from outside data sources to participant residence histories about climate factors, such as heat waves and other disasters, and plan to ask questions about how participants cope and about access to and use of air conditioners and air filters. As we’ve learned how important the social and neighborhood environment can be in shaping exposures and access to medical care and needed services, we’ve been increasingly adding information about the places where study participants live.
During the pandemic, we added questions about COVID infection and about how the pandemic was changing people’s routines, access to care, and psychological stress – all things that could have implications for health down the road. We also continually add questions or ask for more details about certain topics if we discover something interesting and want to dig deeper. One example is the addition of more detailed questions about hair texture and hair product use across the life-course.
What implications will the work have going forward?
Dr. Sandler: We plan to continue the study for many years to come and address issues of relevance to the participants. Breast cancer will continue to be our main focus, but we’ll also keep studying other cancers and chronic diseases, especially those more relevant to an aging population. All the information that we have collected can be important for uncovering causes of other conditions, and we’re partnering with researchers who bring specialized expertise to help us make full use of this data. For example, we’re working with university collaborators to study Parkinson’s disease and diverticulitis.
How did you find your way to the Sister Study?
Dr. Sandler: I was an epidemiologist who studied environmental risk factors for chronic diseases and was intrigued by the public’s call for a study of how changes in the environment could be impacting breast cancer risk. I was part of the team that came up with the original idea for the study and designed the cohort, and I continue to lead it as the study’s Principal Investigator.
Dr. O’Brien: I started working on the Sister Study as a post-doctoral fellow in 2013, a few years after enrollment had completed. I was interested in how social, behavioral, and environmental factors were related to breast cancer, especially breast cancer in young women and racially – or ethnically – minoritized groups. I now serve as Staff Scientist for the study, which means I help facilitate many of our ongoing research projects – everything from designing questionnaires to mentoring young researchers to collaborating with researchers across the globe.
What does this work mean to you?
Dr. Sandler: The Sister Study researchers are passionate about learning more about breast cancer so we can help lower the burden of disease for future generations. We hope the knowledge gained from our research will help guide decision-making at the individual, clinical, and policy levels. In addition, the scope of the study has provided an opportunity to bring in early career researchers who have used the data to ask important new questions. It’s especially exciting to be motivating the next generation of scientists who will continue to study the many factors that contribute to breast cancer.
Anything else you feel is important to say about the study or your work there that we haven’t touched on?
Dr. O’Brien: An important part of the study that should not be overlooked is the dedication of the study participants who have been especially committed to this effort over the years. So many of those who enrolled continue to respond enthusiastically to our requests for updates. Some keep up with what we’re learning by actively following our Facebook posts. And others reach out to us from time to time with questions or suggestions for how we can do even better. It’s great to be part of a study that is meaningful to both the research team and the study participants.
Where do you find sanctuary?
Dr. Sandler: I love being on or near the water and try to spend as much time as possible at the beach on the North Carolina coast.
Dr. O’Brien: I like going on long walks with my dog.
About Dale Sandler, Ph.D.:
The Chronic Disease Epidemiology Group is headed by Dale Sandler, Ph.D., who also is Chief of the Epidemiology Branch in the Division of Intramural Research at NIEHS. Dale is adjunct professor of Epidemiology in the Gillings School of Global Public Health, University of North Carolina at Chapel Hill. In 2015, she won the Nathan Davis Award for Outstanding Government Service from the American Medical Association. She has received several NIEHS and NIH merit awards and received awards for mentoring in 2013 and 2019.
Dale is Principal Investigator of The Sister Study, a prospective cohort of over 50,000 women with enhanced risk for breast cancer due to having had a sister who was diagnosed with the disease. Dale’s group studies early life, reproductive, dietary, lifestyle, and environmental factors related to breast cancer risk. The group studies genetic factors (e.g. gene variation, telomere length, methylation) in relation to breast and other cancers through collaborations with other NIEHS groups and participation in large consortia. Using this cohort, the Chronic Disease Epidemiology group also studies other conditions, including obesity, thyroid disease, diabetes, autoimmune diseases, hypertension, and neurological health.
About Katie O'Brien, Ph.D.:
Katie M. O’Brien, Ph.D., is a staff scientist in the Epidemiology Branch, where she helps lead the Sister Study. Within the study, Katie’s main interests include how environmental and hormone-related exposures are related to breast, ovarian and uterine cancers. With support from the Office of Dietary Supplements Research Scholars Program, she has conducted several studies of the association between vitamin D and breast cancer, including a recent focus on the role of race and ethnicity in this relationship. O’Brien is also interested in understanding how personal care product use, including douching and genital talc use, may affect the risk of reproductive tract cancers (ovarian, uterine, and cervical). She completed a post-doctoral fellowship in the Biostatistics and Computational Biology Branch and continues to be interested in epidemiologic study design and methods issues, particularly those related to the assessment of environmental biomarkers.
The Chronic Disease Epidemiology Group is headed by Dale Sandler, Ph.D., who also is Chief of the Epidemiology Branch in the Division of Intramural Research at NIEHS. Dale is adjunct professor of Epidemiology in the Gillings School of Global Public Health, University of North Carolina at Chapel Hill. In 2015, she won the Nathan Davis Award for Outstanding Government Service from the American Medical Association. She has received several NIEHS and NIH merit awards and received awards for mentoring in 2013 and 2019.
Dale is Principal Investigator of The Sister Study, a prospective cohort of over 50,000 women with enhanced risk for breast cancer due to having had a sister who was diagnosed with the disease. Dale’s group studies early life, reproductive, dietary, lifestyle, and environmental factors related to breast cancer risk. The group studies genetic factors (e.g. gene variation, telomere length, methylation) in relation to breast and other cancers through collaborations with other NIEHS groups and participation in large consortia. Using this cohort, the Chronic Disease Epidemiology group also studies other conditions, including obesity, thyroid disease, diabetes, autoimmune diseases, hypertension, and neurological health.
About Katie O'Brien, Ph.D.:
Katie M. O’Brien, Ph.D., is a staff scientist in the Epidemiology Branch, where she helps lead the Sister Study. Within the study, Katie’s main interests include how environmental and hormone-related exposures are related to breast, ovarian and uterine cancers. With support from the Office of Dietary Supplements Research Scholars Program, she has conducted several studies of the association between vitamin D and breast cancer, including a recent focus on the role of race and ethnicity in this relationship. O’Brien is also interested in understanding how personal care product use, including douching and genital talc use, may affect the risk of reproductive tract cancers (ovarian, uterine, and cervical). She completed a post-doctoral fellowship in the Biostatistics and Computational Biology Branch and continues to be interested in epidemiologic study design and methods issues, particularly those related to the assessment of environmental biomarkers.
