Recreational physical activity during adolescence may be associated with changes in breast tissue composition and biological markers of stress, potentially influencing future breast cancer risk, according to a new study led by researchers at Columbia University’s Mailman School of Public Health and the Herbert Irving Comprehensive Cancer Center (HICCC).
While decades of research in adult women have consistently shown that higher levels of recreational physical activity are linked to a reduced risk of breast cancer—by as much as 20 percent among the most active women—the biological pathways behind this protective effect, particularly earlier in life, have remained unclear. The new findings, published in Breast Cancer Research, offer some of the first evidence connecting physical activity during adolescence, a critical window of breast development, to measurable biological changes.
The study found that adolescent girls who engaged in at least two hours of recreational physical activity in the previous week had lower percent water content in breast tissue, a marker associated with lower breast density. High breast density is a well-established predictor of breast cancer risk. These girls also showed lower levels of urinary biomarkers linked to stress, suggesting that physical activity may influence stress-related biological pathways independent of body fat.
“Our findings suggest that recreational physical activity is associated with breast tissue composition and stress biomarker changes in adolescent girls, independent of adiposity, which could have important implications for breast cancer risk,” said Rebecca Kehm, PhD, assistant professor of epidemiology at Columbia Mailman School of Public Health and first author of the study. She noted that the research comes amid rising rates of breast cancer among younger women and persistently low levels of physical activity among adolescents in the United States and worldwide.
Researchers analyzed data from the population-based Columbia Breast Cancer and the Environment Research Program Study, which draws on the Columbia Center for Children’s Environmental Health Mothers and Newborns birth cohort. Participants were originally recruited between 1998 and 2006 from prenatal clinics at NewYork-Presbyterian Hospital, Harlem Hospital, and affiliated clinics serving urban communities including Washington Heights, Central Harlem, and the South Bronx.
During adolescence, participants self-reported their engagement in recreational physical activity over the prior week, including both organized and unorganized activities. They also attended clinic visits where blood and urine samples were collected and breast tissue assessments were conducted. The average age of participants was 16, with 64 percent identifying as Hispanic. More than half of the girls reported no recreational physical activity in the previous week, highlighting what researchers described as alarmingly low activity levels.
Mary Beth Terry, PhD, professor of epidemiology at Columbia Mailman School and senior author of the study, said the research was strengthened by the use of multiple validated biomarkers measured across urine, blood, and breast tissue. “Importantly, this study 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,” she said.
Kehm added that the focus on urban Hispanic and non-Hispanic Black adolescent girls is especially significant, as these populations face higher risks of developing breast cancer at younger ages and are more likely to experience aggressive subtypes of the disease, while also reporting lower levels of recreational physical activity than their non-Hispanic White peers.
The authors caution that further longitudinal studies are needed to determine how these adolescent biomarkers translate into breast cancer risk later in life. However, they say the findings underscore the potential importance of promoting physical activity early in development as part of long-term cancer prevention strategies.
The study was supported by grants from the National Institute of Environmental Health Sciences and the National Cancer Institute, with additional contributions from researchers at Columbia University, the Icahn School of Medicine at Mount Sinai, and the University of Toronto.
