Study links physical activity in adolescents to biomarkers of breast cancer risk

Study links physical activity in adolescents to biomarkers of breast cancer risk

Recreational physical activity may be associated with breast tissue composition and biomarkers of stress in adolescent girls, according to a new study from Columbia University's Mailman School of Public Health and the Herbert Irving Comprehensive Cancer Center (HICCC). The findings shed new light on how physical activity during adolescence – a critical period of breast development – ​​may influence biological pathways related to future breast cancer risk.

In adult women, higher levels of recreational physical activity (RPA) are consistently associated with a lower risk of breast cancer. Studies show that the risk decreases by about 20 percent for the most active women compared to the least active women. However, to date, the biological mechanisms underlying this relationship - particularly in early life - are poorly understood. The new study provides some of the first evidence linking RPA to breast tissue composition and stress-related biomarkers in adolescent girls. The results will be published in the journalBreast cancer research.

The importance and urgency of this research is underscored by the increasing incidence of breast cancer in young women and the alarmingly low levels of leisure-time physical activity observed both in this study and among adolescents in the United States and worldwide. Our results suggest that leisure-time physical activity is associated with breast tissue composition and stress biomarker changes in adolescent girls, independent of body fat, which may have important implications for breast cancer risk.”

Rebecca Kehm, PhD, assistant professor of epidemiology at the Columbia Mailman School of Public Health and first author of the study

Girls who reported engaging in at least two hours of leisure-time physical activity in the previous week had lower percent water content in breast tissue - an indicator of lower breast density - and lower concentrations of stress-related biomarkers in urine compared to no girls. These results are consistent with previous research in adult women showing that higher levels of physical activity are associated with lower mammographic breast density, an important predictor of breast cancer risk. Researchers analyzed data from the population-based Columbia Breast Cancer and the Environment Research Program study, which is based on the Columbia Center for Children's Environmental Health (CCCEH) Maternal and Newborn Birth Cohort. Participants were originally recruited to the cohort between 1998 and 2006 from prenatal clinics at NewYork-Presbyterian and Harlem Hospital, as well as affiliated satellite clinics that served neighborhoods such as Washington Heights, Central Harlem, and the South Bronx.

During puberty, participants self-reported that they had been physically active in the past week, including organized and unorganized activities, and that they had completed clinic visits that included blood and urine collection and breast tissue assessment.

The average age of the girls in the study was 16 and 64 percent identified as Hispanic. More than half (51 percent) said they had not done any physical leisure activity in the past week. 73 percent reported not participating in organized activities and 66 percent reported not participating in 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 of the study. "We measured biomarkers of stress and chronic inflammation that are widely validated and commonly used in epidemiological research, increasing confidence in our results. Importantly, this research was conducted in a population-based, urban cohort of Black/African American and Hispanic girls groups, who have been historically underrepresented in research and have 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 for inclusion in breast cancer research,” added Kehm, who is also a member of the HICCC. "Not only have these groups been historically underrepresented in studies, but they are also at higher risk of developing breast cancer at younger ages and more aggressive subtypes. At the same time, Black and Hispanic girls consistently report lower levels of leisure-time physical activity than their non-Hispanic white peers."

The authors note that additional longitudinal studies are needed to determine how these biomarkers may impact breast cancer risk in adolescents later in life, and say the results underscore the potential importance of promoting physical activity early in development.

Co-authors are: Lothar Lilge, Princess Margaret Cancer Centre, University Health Network, Toronto and University of Toronto; E. Jane Walter, Princess Margaret Cancer Center, University Health Network; Regina Santella, Melissa L. White, Julie Herbstman and Frederica Perera, Columbia Mailman School of Public Health; and Rachel L. Miller, Icahn School of Medicine at Mount Sinai.

The study was supported by the National Institute of Environmental Health Sciences grants U01ES026122 and P30ES009089; and the National Cancer Institute, grant R00CA263024.

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