- Adolescent physical activity may influence breast tissue and cancer risk in girls.
- A study associates exercise with lower breast density and reduced stress biomarkers in youth.
- Breast cancer is being diagnosed in younger women more than in the past.
Recreational physical activity or its lack could be a factor in whether an adolescent girl develops breast cancer later.
That’s according to findings of a study from Columbia University’s Mailman School of Public Health, which highlights that adolescence is a “critical period for breast development” and could influence future breast cancer development.
According to a news release about the study, which was published in the journal Breast Cancer Research, adult women who are highly engaged in recreational physical activity have a roughly 20% reduction in breast cancer risk compared to less active women. But the “why” has not been well understood and that’s what the researchers set out to try to solve, with a study involving adolescent females.
“The new study provides some of the first evidence linking (recreational physical activity) to breast tissue composition and stress-related biomarkers in adolescent girls,” per the release.
Per the release, “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,” said Rebecca Kehm, an assistant professor of Epidemiology at Columbia Mailman School of Public Health and the study’s first author. “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.”
Researchers are careful to note they found an association, not causation.
Breast cancer in younger and younger women
In unrelated research, Memorial Sloan Kettering Cancer Center last year noted that many cancers are being diagnosed at much younger ages, including breast cancer. And those cancers are increasingly seen in young women.
Additionally, many of the cases diagnosed in young people are aggressive. The cancer center’s article noted that “more dangerous breast cancer subtypes are appearing in younger women.”
Obesity, environmental risks and lack of exercise are among potential explanations, according to a number of studies.
What researchers looked for
Breast density is a valuable consideration in predicting breast cancer. Cancer is harder to detect early in dense breasts.
As News Medical put it, “A growing body of evidence indicates that adolescence represents a ‘window of susceptibility,’ a period characterized by rapid mammary gland development during which the breast is particularly sensitive to external influences.”
In the Columbia study, girls who were physically active for at least two hours in the past week had less water content in their breast tissue, which indicates lower breast density. They also had lower concentrations of the biomarkers linked to stress in urine. The findings are very much like previous studies in adult women.
The researchers looked at data from the Columbia Breast Cancer and the Environment Research Program Study, which draws from the Columbia Center for Children’s Environmental Health Mothers and Newborns birth cohort. As part of the study, teens reported on their past-week recreational physical activity, both organized and not. They also provided blood and urine samples and had breast tissue assessment.
On average, the girls were 16. The researchers focused on Black or Hispanic teens because those groups are seldom included in research and they have identified disparities in physical activity and breast cancer outcomes.
“These groups not only have been historically underrepresented in studies, but they face higher risks of developing breast cancer at young ages and of experiencing more aggressive subtypes,” said Kehm. “At the same time, Black and Hispanic girls consistently report lower levels of recreational physical activity than their non-Hispanic White peers.”
Just over half reported no recreational physical activity in the past week, while 73% said they did not participate in organized activities and two-thirds said they didn’t do unorganized recreational activities, either.
The researchers said they plan longitudinal research to see how the teen biomarkers affect future breast cancer risk, but note the research already shows the importance of physical activity for youths.