October is National Breast Cancer Awareness Month, and at NIEHS, the spotlight is on prevention. Our research is dedicated to better understanding how exposures may be linked to the onset of breast cancer.
The highlights below feature work by scientists in the National Toxicology Program (NTP), which is housed at the institute, as well as two large research programs — the Sister Study and the Breast Cancer and the Environment Research Program (BCERP).
National Toxicology Program
The NTP laboratory of Sue Fenton, Ph.D., focuses on the role of environmental chemicals in breast developmental timing as it relates to puberty, altered lactiational ability, and increased susceptibility to breast cancer. In July, her team published a technique to improve identification of lesions in mammary tissue.
The researchers studied rodent mammary glands for potential effects of chemical exposures. They found discrepancies between tissue samples from the same animal, depending on the technique used to prepare and analyze the sample.
This led them to refine an existing technique and demonstrate that using it, together with the standard approach, led to more accurate identification of lesions. The paper and video of the technique were published July 24 in the video journal JoVE.
"Our findings may help reduce the chance of missing the effects stemming from exposure to a particular chemical," said lead author Dierdre Tucker, a predoctoral fellow in Fenton’s lab. "The first step in preventing exposure to cancer-causing substances is to properly identify carcinogens that we may be exposed to singly or in mixtures."
The Sister Study
The Sister Study is a long-term study of sisters of women with breast cancer. Dale Sandler, Ph.D., head of the NIEHS Epidemiology Branch, and Clarice Weinberg, PhD., acting head of the NIEHS Biostatistics and Computational Biology Branch, lead the project.
"We designed this study specifically to help researchers better understand relationships between environmental and genetic factors in breast cancer," Sandler said. "By following participants over the long term, we are discovering how exposures, including behaviors, interact with genetic characteristics."
The latest findings from Sister Study researchers involved topics such as oxidative stress, binge drinking, postmenopausal estrogen levels, physical activity, vitamin D, and numerous other exposures and genetic factors. A full list of papers is available on the study’s website.
Breast Cancer and the Environment Research Program
In 2015, NIEHS and the National Cancer Institute announced a new group of grantees in the jointly-funded BCERP program. "We combine laboratory work, clinicians, and community outreach activities all into one grant," explained Abee Boyles, Ph.D., who serves as the NIEHS lead for BCERP.
Current projects focus on involving racially and ethnically diverse communities, working across different scientific disciplines, and expanding the study of risk factors that precede breast cancer, such as breast density. The latest round also included new grants devoted to communications research. These grantees study messages and communication approaches to determine the best ways to reduce disease risk from exposures.
The scientists are particularly interested in the stages of life at which a body is especially vulnerable to exposures. Such windows of susceptibility, as they are known, include fetal development and early childhood; puberty; and menopausal transition.
At a July BCERP meeting, nearly two dozen scientists gathered to learn about evaluating mammary whole mounts from Jose Russo, M.D., from Fox Chase Cancer Center. Fenton, from NTP, presented the sectioning method described above and discussed details of rat mammary gland development, which are relevant to the study of endocrine disruptors.
Members of the network will gather Nov. 16-17 for a public meeting in Monrovia, California on the theme, Translating Research Into Action to Reduce Breast Cancer. In conjunction with the meeting, NIEHS will hold a community forum (see sidebar).
Highlights from recent publications by NIEHS-funded researchers — both grantees and in-house scientists at NIEHS and NTP — are presented below.
- Sectioning mammary gland whole mounts for lesion identification.
- Effects of perfluorinated chemicals on thyroid function, markers of ovarian reserve, and natural fertility.
- Differences in the rate of in situ mammary gland development and other developmental endpoints in three strains of female rat commonly used in mammary carcinogenesis studies: implications for timing of carcinogen exposure.
- Mammary gland evaluation in juvenile toxicity studies: temporal developmental patterns in the male and female Harlan Sprague-Dawley rat.
- Oxidative stress and breast cancer risk in premenopausal women.
- Lifetime alcohol intake, binge drinking behaviors, and breast cancer risk.
- Serum vitamin D and risk of breast cancer within five years.
- Systemic levels of estrogens and PGE2 synthesis in relation to postmenopausal breast cancer risk.
- Childhood and teenage physical activity and breast cancer risk.
- Scientific message translation and the heuristic systematic model: insights for designing educational messages about progesterone and breast cancer risks.
- Associations of urinary phthalate and phenol biomarkers with menarche in a multiethnic cohort of young girls.
- Pubertal and adult windows of susceptibility to a high animal fat diet in Trp53-null mammary tumorigenesis.