Questions and answers about the new breast cancer risk models
- What did the researchers find?
- What was the most surprising finding?
- What is breast density?
- How is breast density determined?
- How will these new findings affect breast cancer screening?
- What can women do to reduce their risk of breast cancer?
- How was the study conducted?
- Who conducted the study?
What did the researchers find?
In developing a new model to assess risks for breast
cancer, the researchers identified several factors, which differed
slightly between pre- and postmenopausal women. In pre-menopausal women,
risk factors included greater age, higher breast density, family history
of breast cancer, and a prior breast procedure. In postmenopausal women,
risk factors also included ethnicity, greater body mass index, natural
menopause, use of hormone therapy, and a prior false-positive mammogram,
as well as the risk factors found in pre-menopausal women.
Their research appears in the September 6 issue of the Journal of the National Cancer Institute.
What was the most surprising finding?
The most surprising finding was that breast density is
nearly as important as age in determining a woman's risk of developing
breast cancer, even after taking into account other related factors.
For example, after adjustment for age, the risk for women with highly
dense breasts was more than three times greater than that for women whose
breasts were the least dense.
What is breast density?
Breast density is a measure of how well tissue can be
seen on mammogram. Some tissue, such as the milk gland, is dense and
appears white on an x-ray, making tumors, which also appear white, harder
to see. Fatty tissue is less dense and appears clear on the x-ray,
allowing better tumor detection.
How is breast density determined?
Radiologists who examine x-rays of breast tissue assign
a score of one to four based on how clear or opaque the breast tissue
appears. A score of one is the lowest and a score of four is the highest.
Although this is a subjective measure by individual radiologists, there
are guidelines for using the four breast density values.
How will these new findings affect breast cancer
screening?
It's too soon to tell. With more research to validate
the models, doctors might use breast density, along with other risk
factors, to identify women who could benefit from preventive interventions
or more intensive screening. Currently, however, the models cannot be
used to predict the development cancer in individual women.
What can women do to reduce their risk of breast cancer?
- Get breast cancer screening as recommended by their doctors.
- Avoid hormone therapy if possible.
- Practice a healthy lifestyle that includes plenty of physical activity and a low-fat diet.
- Promptly report any symptoms or concerns about their breasts.
- If they have concerns about their breast density, discuss them with their doctors.
How was the study conducted?
Researchers examined breast cancer risk factor data
collected on more than 1 million women from the United States at the time
of their screening mammogram and identified all women who were diagnosed
with breast cancer within the next year. A total of 11,638 women were
diagnosed with breast cancer. The information on women who did and did not
develop breast cancer was used to develop and validate risk prediction
models.
Who conducted the study?
Scientists involved in the Breast Cancer Surveillance
Consortium, including:
- William E. Barlow, PhD, lead investigator, Group Health Center for Health Studies, and Cancer Research and Biostatistics, Seattle
- Emily White, PhD, University of Washington, Seattle
- Rachel Ballard-Barbash, MD, MPH, National Cancer Institute
- Pamela M. Vacek, PhD, University of Vermont
- Linda Titus-Ernstoff, PhD, Dartmouth Medical School
- Patricia A. Carney, PhD, Oregon Health and Sciences University
- Jeffrey A. Tice, MD, University of California, San Francisco
- Diana S. M. Buist, PhD, MPH, Group Health Center for Health Studies, Seattle
- Berta M. Geller, EdD, University of Vermont
- Robert Rosenberg, MD, University of New Mexico
- Bonnie C. Yankaskas, PhD, University of North Carolina
- Karla Kerlikowske, MD, University of California, San Francisco
The study was funded by the National Cancer Institute.