New Study Links Physical Activity in Girls to Lower Breast Cancer Risk

A recent study conducted by researchers at Columbia University has revealed that physical activity during adolescence may influence breast cancer risk later in life. The research indicates that girls engaging in at least two hours of recreational physical activity weekly show lower breast density and reduced stress markers, both of which are associated with a decreased risk of breast cancer.

The findings stem from a study involving nearly 200 Black and Hispanic girls from New York City, with an average age of 16 years. Participants reported their activity levels, with more than half indicating they had not engaged in any recreational physical activity in the past week. Over 66 percent of the girls did not take part in unorganized activities, while close to 75 percent did not participate in organized activities.

Impact of Physical Activity on Breast Density and Stress Markers

Research has long established that women who maintain higher levels of physical activity have a lower risk of developing breast cancer—approximately 20 percent lower for the most active individuals. The current study reinforces this by suggesting that the benefits of physical activity extend to adolescent girls, influencing breast tissue composition.

Dr. Rebecca Kehm, an assistant professor of epidemiology at Columbia’s Mailman School of Public Health, emphasized the significance of these findings: “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.”

The study included assessments of blood and urine samples, as well as tissue evaluations during visits to Columbia. Dr. Mary Beth Terry, another professor of epidemiology, noted the reliability of the biomarkers used in the research: “We measured biomarkers of stress and chronic inflammation that are widely validated and commonly used in epidemiologic research, enhancing confidence in our findings.”

Breast Density and Its Implications

Breast density, characterized by a higher proportion of fibrous and glandular tissue relative to fatty tissue, affects nearly half of all women, as stated by the Cleveland Clinic. It is primarily influenced by hormone levels during adolescence and is a recognized risk factor for breast cancer. Higher breast density can complicate the detection of abnormalities in mammograms, although it does not increase the likelihood of mortality from the disease.

The relationship between physical activity and breast density appears to be significant, with girls who engaged in the recommended levels of activity displaying lower water content in their breast tissue—an indicator of reduced density.

These findings are especially pertinent given the rising incidence of breast cancer among adults under 50 years old in the United States. Recent statistics indicate that the number of early cases has steadily increased over the past two decades, with a sudden surge of 3.76 percent between 2016 and 2019, according to doctors at Washington University in St. Louis. This year, it is anticipated that there will be over 321,000 new cases and more than 42,000 deaths from breast cancer among women of all ages.

Dr. Kehm pointed out that Black and Hispanic women face a disproportionate risk at younger ages. She noted, “At the same time, Black and Hispanic girls consistently report lower levels of recreational physical activity than their non-Hispanic white peers.” This disparity underscores the need for targeted interventions to promote physical activity among these populations.

Further research is necessary to explore how these markers in adolescents may translate into breast cancer risk in adulthood, but the current study clearly highlights the importance of physical activity for young girls’ long-term health.