A new Columbia University study suggests that even modest recreational exercise in teen girls may influence breast tissue and stress biomarkers tied to future breast cancer risk. The work highlights adolescence as a key window for prevention, especially for Black and Hispanic youth.
Recreational exercise in the teen years may do more than boost mood and fitness. It could also influence biological markers tied to future breast cancer risk, according to a new study from Columbia University Mailman School of Public Health and the Herbert Irving Comprehensive Cancer Center.
The researchers found that adolescent girls who reported at least two hours of recreational physical activity in the previous week had different breast tissue composition and lower levels of stress-related biomarkers than girls who reported no activity. The study, published in the journal Breast Cancer Research, offers some of the first evidence that what girls do with their free time in high school could affect biological pathways linked to breast cancer later on.
In adult women, higher levels of recreational physical activity have long been associated with a lower risk of breast cancer, with the most active women showing about a 20% lower risk than the least active. But scientists have not fully understood how, or whether, habits earlier in life help set that risk.
First author Rebecca Kehm, an assistant professor of epidemiology at Columbia Mailman, noted that the new findings point to adolescence as a critical window.
“The importance and urgency of this research are underscored by the rising incidence of breast cancer in young women and the alarmingly low levels of recreational physical activity observed both in this study and among adolescents across the United States and globally,” she said in a news release.
The team drew on data from the Columbia Breast Cancer and the Environment Research Program Study, which follows participants from the Columbia Center for Children’s Environmental Health Mothers and Newborns birth cohort. Families were originally recruited between 1998 and 2006 from prenatal clinics at NewYork-Presbyterian, Harlem Hospital and affiliated clinics serving neighborhoods including Washington Heights, Central Harlem and the South Bronx.
As adolescents, participants reported how much recreational physical activity they had done in the past week, including both organized activities like sports teams and unorganized activities such as informal games or exercise. They also came to clinic visits where researchers collected blood and urine samples and assessed breast tissue.
On average, the girls were 16 years old, and nearly two-thirds identified as Hispanic. Yet more than half reported no recreational physical activity at all in the previous week. Nearly three-quarters said they did not take part in any organized activities, and two-thirds reported no unorganized activities.
Against that backdrop of low activity, the researchers compared girls who reported at least two hours of recreational physical activity in the prior week with those who reported none. The more active girls had lower percent water content in their breast tissue, a measure that reflects lower breast density. In adult women, lower mammographic breast density is a well-established predictor of lower breast cancer risk.
The active girls also had lower concentrations of urinary biomarkers linked to stress. Chronic stress and related biological changes are thought to play a role in cancer development, although the exact mechanisms are still being studied.
Kehm noted that the patterns held even after accounting for body fat, suggesting that the benefits of movement may go beyond weight control.
“Our findings suggest that recreational physical activity is associated with breast tissue composition and stress biomarker changes in adolescent girls, independent of body fat, which could have important implications for breast cancer risk,” she added.
To capture a more complete picture of what was happening in the body, the team measured multiple biomarkers in different types of samples.
“Our research has several strengths, including the use of multiple biomarkers measured in urine, blood, and breast tissue,” added senior author Mary Beth Terry, a professor of epidemiology at Columbia Mailman. “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.”
Kehm emphasized that centering these communities is not just a matter of representation, but of addressing real differences in risk and opportunity.
“Our study population of urban Hispanic (Dominican) and non-Hispanic Black/African American adolescent girls is critical to include in breast cancer research,” she said. “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 study does not prove that exercise in adolescence will prevent breast cancer, and the researchers stress that more work is needed. They call for additional long-term, or longitudinal, studies to track how these adolescent biomarkers relate to actual breast cancer diagnoses later in life.
Still, the findings add to a growing body of evidence that habits formed early in life can have lasting health effects. For public health officials, schools and families, the study underscores the potential power of making it easier and more appealing for girls — especially those in under-resourced urban communities — to be active.
That could mean safer parks and playgrounds, affordable sports programs, culturally relevant activities, and policies that protect and expand physical education and after-school opportunities.
For students and parents, the message is simple but hopeful: even modest amounts of recreational activity, from organized sports to informal movement, may be doing more than building strong muscles. They may also be shaping the biology of breast tissue and stress in ways that could matter decades down the line.