Recreational physical activity in adolescent girls may influence breast tissue composition and stress-related biomarkers, according to a new study from Columbia University Mailman School of Public Health and the Herbert Irving Comprehensive Cancer Center. The research, published in Breast Cancer Research, explores how exercise during adolescence—a key period for breast development—may affect biological pathways tied to future breast cancer risk.
Previous studies have shown that adult women who are more physically active have about a 20 percent lower risk of developing breast cancer compared to those who are less active. However, the mechanisms behind this association, especially earlier in life, have not been well understood. This new study is among the first to link recreational physical activity (RPA) with changes in breast tissue composition and stress biomarkers in adolescent girls.
Researchers found that girls who reported at least two hours of recreational physical activity in the previous week had lower water content in their breast tissue—suggesting lower breast density—and reduced levels of urinary biomarkers associated with stress. These results are consistent with findings from adult populations where increased physical activity correlates with decreased mammographic breast density, an important predictor of breast cancer risk.
The data analyzed came from the Columbia Breast Cancer and the Environment Research Program Study, which includes participants originally recruited between 1998 and 2006 from prenatal clinics at NewYork-Presbyterian and Harlem Hospital as well as affiliated satellite clinics serving urban neighborhoods such as Washington Heights, Central Harlem, and the South Bronx. During adolescence, participants self-reported their recent engagement in both organized and unorganized recreational activities. They also underwent clinic visits for blood and urine collection along with assessments of their breast tissue.
The average age among participants was 16 years old; 64 percent identified as Hispanic. More than half reported no recreational physical activity during the prior week; most did not participate in either organized or unorganized activities.
"Our research has several strengths, including the use of multiple biomarkers measured in urine, blood, and breast tissue," said Mary Beth Terry, PhD, professor of Epidemiology at Columbia Mailman School and senior author on the study. "We measured biomarkers of stress and chronic inflammation that are widely validated and commonly used in epidemiologic research, enhancing confidence in our findings. Importantly, this research was conducted in a population-based, urban cohort of Black/African American and Hispanic girls-groups that are historically underrepresented in research and face persistent disparities in both physical activity levels and breast cancer outcomes."
"Our study population of urban Hispanic (Dominican) and non-Hispanic Black/African American adolescent girls is critical to include in breast cancer research," added Kehm from HICCC. "These groups not only have been historically underrepresented in studies but they face higher risks of developing breast cancer at younger ages and of experiencing more aggressive subtypes. At the same time, Black and Hispanic girls consistently report lower levels of recreational physical activity than their non-Hispanic White peers."
The authors state that further longitudinal studies will be necessary to understand whether these adolescent biomarkers relate directly to future risk for developing breast cancer. They emphasize that encouraging physical activity early could be important for long-term health outcomes.
Co-authors include researchers from Princess Margaret Cancer Centre/University Health Network Toronto; University of Toronto; Icahn School of Medicine at Mount Sinai; as well as several faculty members from Columbia Mailman School.
The project received funding support from grants provided by the National Institute of Environmental Health Sciences (U01ES026122; P30ES009089) as well as by a grant from the National Cancer Institute (R00CA263024).
