A new study led by researchers at Columbia University suggests that recreational physical activity during adolescence may play an important role in shaping breast tissue composition and reducing biological markers of stress—two factors closely linked to future breast cancer risk.
The findings come amid growing concern over rising breast cancer rates among younger women and persistently low levels of physical activity among adolescents. “The importance and urgency of this research are underscored by the increasing incidence of breast cancer in young women and the alarmingly low levels of recreational physical activity observed both in our study and among adolescents nationwide and globally,” said lead author Rebecca Kehm, an assistant professor of epidemiology at the Columbia Mailman School of Public Health.
The study analyzed data from African American and Hispanic (Dominican) girls enrolled in the Columbia Breast Cancer and the Environment Research Program Study. Researchers examined participants’ self-reported recreational physical activity over the previous week alongside clinical data collected during study visits, including breast tissue assessments and blood and urine samples. The participants were originally recruited from prenatal clinics serving urban neighborhoods in New York City.
Researchers found that girls who reported at least two hours of recreational physical activity in the prior week had lower percentages of water in their breast tissue and reduced levels of urinary stress-related biomarkers compared with those who reported no exercise. These results are consistent with previous studies in adult women showing that higher physical activity levels are associated with lower mammographic breast density—a known indicator of reduced breast cancer risk.
Despite these potential benefits, physical activity levels among participants were notably low. More than half of the girls reported no recreational physical activity in the prior week. Nearly three-quarters said they did not take part in organized physical activities, while about two-thirds reported no involvement in unorganized activities.
Dr. Kehm emphasized the importance of focusing on populations that are often underrepresented in breast cancer research. “Our study population of urban Hispanic (Dominican) and non-Hispanic Black/African American adolescent girls is critical,” she said. “These groups face higher risks of developing breast cancer at younger ages and are more likely to experience 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 research team also included scientists from the Princess Margaret Cancer Centre and the University of Toronto in Canada, as well as the Icahn School of Medicine at Mount Sinai in New York.
