Lifetime physical activity and breast cancer risk

The Introduction

breast cancerPhysical activity is associated with a lower risk of breast cancer. Most studies have demonstrated a reduction in risk of on average 30-40% among the most physically active women compared with the least active. The link between breast cancer and physical activity was also found to be stronger in post-menopausal than pre-menopausal women. However, research findings are inconsistent regarding the type, duration, intensity, and frequency of physical activity that is needed to reduce the risk of breast cancer. This study looked to determine whether the intensity of physical activity reduced the risk of breast cancer.

The Research

The Polish researcher examined the effect of physical activity on breast cancer risk among 858 Polish women with breast cancer and compared her results with 1085 controls that had no breast cancer. She collected data on lifetime household, occupational, and recreational activities using a self-administered questionnaire and divided the women into three groups according to their activity levels – low, moderate and vigorous intensity.

The Results

The results showed that moderate- and vigorous-intensity total and recreational activities, as well as moderate- and long-lasting low-intensity household activities, lead to reduced breast cancer risk in a dose – response manner, independent of menopausal status. The most marked and consistent reductions in breast cancer risk for lifetime low-intensity household and vigorous-intensity recreational activities were found among post-menopausal rather than pre-menopausal women.

The So What?

The American Institute for Cancer Research suggest the accumulation of at least 30-60 min daily of moderate- to vigorous-intensity activity at least 5 days a week. This Polish study shows that moderate-intensity lifetime total activity of at least 3.1 hours per week per year is sufficient to protect pre-menopausal women but may be insufficient for post-menopausal women. The post-menopausal women required a longer duration of moderate- or vigorous-intensity activity. Instead, vigorous-intensity activity of at least 2.6 hours per week per year resulted in a 50% risk reduction in both menopausal groups. Great news for older female masters athletes who regularly train vigorously.

Kruk, J. (2009). Intensity of lifetime physical activity and breast cancer risk among polish women. Journal of Sports Sciences, 27(5): 437-445.