Daijiworld Media Network – New Delhi

New Delhi, Jan 20: A recent study published in the journal Breast Cancer Research has found that adolescent girls who engage in regular organised physical activity show favourable changes in breast tissue composition and lower levels of oxidative stress — biomarkers that are linked to breast cancer risk later in life.

The study analysed data from 191 adolescent girls aged between 11 and 20 years, predominantly from historically underrepresented communities, including Hispanic and Black/African American populations. Researchers examined the association between recreational physical activity (RPA) during adolescence and biological markers related to breast cancer risk using non-invasive optical spectroscopy and laboratory biomarker analysis.

Researchers observed that girls who participated in at least two hours of organised physical activity, such as sports teams or dance classes, in the previous week had significantly lower breast water content. This measure is positively correlated with mammographic breast density in adults — a known predictor of breast cancer risk — though it is not identical. These girls also exhibited lower levels of oxidative stress, a factor linked to cellular damage.

However, the authors cautioned that the study was cross-sectional in nature and relied on self-reported activity data, meaning a direct causal relationship cannot be established.

Breast cancer remains the most commonly diagnosed cancer among women worldwide, with around 2.3 million new cases each year. While previous research has shown that physical activity in adulthood can reduce breast cancer risk by nearly 20%, the impact of exercise during adolescence has been less clearly understood.

Scientists increasingly recognise adolescence as a “window of susceptibility”, a period of rapid breast development during which external factors such as physical activity may influence long-term breast health.

High mammographic breast density — the proportion of fibroglandular tissue compared to fat — is a strong predictor of breast cancer in adults. However, limited data exist on how modifiable lifestyle factors during puberty affect breast tissue composition linked to density.

The issue is particularly significant for Black/African American and Hispanic populations, who face a higher risk of aggressive, early-onset breast cancer and report lower levels of physical activity.

Study design and findings

The study used data from the Columbia Breast Cancer and the Environment Research Program (Columbia-BCERP), an urban, population-based cohort in the United States. Breast tissue composition was assessed using optical spectroscopy, which measures water, collagen and lipid content in breast tissue using red and near-infrared light.

Participants reported their physical activity over the past week, which was classified as organised (structured sports or classes) or unorganised (casual play or cycling).

Alarmingly, 51% of the participants reported no recreational physical activity in the previous week, while 73% said they did not take part in any organised activities, highlighting high inactivity levels among adolescent girls in these communities.

Girls who engaged in two or more hours of organised activity had lower breast water content even after adjusting for body fat, suggesting the association was not solely due to differences in weight or adiposity. They also had lower levels of 15-F2t-isoprostane, a urinary marker of oxidative stress.

Interestingly, the study did not find significant associations between physical activity and markers of chronic inflammation such as C-reactive protein (CRP), interleukin-6 (IL-6) or tumour necrosis factor-alpha (TNF-α).

Researchers also observed that higher oxidative stress levels were associated with greater collagen content in breast tissue, indicating a possible biological link between stress and fibroglandular tissue development, though causality remains unclear.

The findings suggest that participation in organised physical activity during adolescence may be associated with biological markers linked to lower breast cancer risk. While the study does not prove long-term cancer prevention, it highlights the potential importance of structured physical activity during critical developmental years.

The authors stressed the need for public health initiatives to improve access to organised sports and physical activity for adolescent girls, particularly in underserved communities. They also called for long-term studies to determine whether these early biological changes persist into adulthood and translate into reduced breast cancer incidence.