Physical activity linked to breast tissue changes in adolescent girls

Researchers have linked recreational physical activity (RPA) to breast tissue composition and biomarkers of stress in adolescent girls, publishing their findings in Breast Cancer Research.¹

Prior research has highlighted reduced odds of breast cancer from RPA in adult women, but data in adolescents and about the biological mechanisms underlying this association has remained limited. According to investigators, these new findings elaborate on the impact of RPA toward biological pathways influencing future breast cancer risk.¹

“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,” said Rebecca Kehm, PhD, first study author and assistant professor at Columbia Mailman School of Public Health.¹

Study design and evaluated biomarkers

The study was conducted to evaluate the link between RPA and biomarkers of breast cancer in adolescent girls.² Biomarkers evaluated included breast tissue composition (BTC), oxidative stress, and inflammation. Investigators also assessed the link between oxidative stress and inflammation with BTC among this population.

Data was obtained from the Columbia Breast Cancer and the Environment Research Program Study, which included patients recruited from prenatal clinics between 1998 and 2006.¹ Participants were aged a mean 16 years, and 64% were Hispanic.

Black and Hispanic girls aged 11 to 20 years were included in the analysis.² The primary exposure among these patients was the number of hours spent engaging in organized and unorganized RPA. This exposure was self-reported, and categories included under 2 hours and at least 2 hours.²

BTC was measured using optical spectroscopy. Additionally, urinary concentrations of 15-F2t-isoprostane were measured as marker of oxidative stress. Blood biomarkers of inflammation such as TNF-α, IL-6, and high-sensitivity C-reactive protein were also obtained. Covariates included race and ethnicity, age, and percent body fat.²

Key findings on breast tissue composition and oxidative stress

There were 191 participants included in the final analysis, 51% of whom reported no past-week RPA of any type, 73% no organized RPA, and 66% no unorganized RPA. A lower percent of water content in the breast was reported in the breasts of adolescents with at least 2 hours of organized RPA (β: − 0.41).

Urinary 15-F2t-isoprostane concentrations were also reduced among these patients (β: − 0.50+. Increased 15-F2t-isoprostane concentrations were linked to a greater percent of collagen content in the breast, (β: 0.1).²

There were no associations reported between RPA and inflammatory biomarkers. Additionally, after adjustment for percent body fat, no link was found between these biomarkers with BTC.²

Implications for future breast cancer research

Overall, these results indicated a link for RPA with BTC and oxidative stress among adolescent girls that is independent of body fat. Investigators recommended additional longitudinal research to evaluate how these associations influence future breast cancer risk.²

“Our study population of urban Hispanic (Dominican) and non-Hispanic Black/African American adolescent girls is critical to include in breast cancer research,” said Kehm. “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.”

References

1. Breast cancer risk markers linked to physical activity in adolescent girls. Columbia University’s Mailman School of Public Health. January 15, 2026. Accessed January 19, 2026. https://www.eurekalert.org/news-releases/1112825
2. Kehm RD, Lilge L, Walter JE, et al. Recreational physical activity and biomarkers of breast cancer risk in a cohort of adolescent girls. Breast Cancer Research. 2026. doi:10.1186/s13058-025-02216-1