Physical activity is one of the leading ways to prevent cancer with estimates concluding 30% of cancers in the US could be improved through improvements to diet, obesity and exercise behaviors. Despite the cancer and other chronic disease benefits from physical activity, the majority of the US population remains inactive. Efforts to implement cancer prevention through physical activity are met with questions about the specifics of the relation between physical activity and cancer: Everyone? How much? How hard?

Evidence is accumulating that physical activity across the lifecourse is important for cancer prevention. In addition to reducing risk of colon cancer by more than 20%, physical activity also reduces risk of colon polyps. Lifetime physical activity levels are consistently related to several cancers. Adolescent physical activity is associated with a reduced risk of colon cancer. This epidemiologic evidence has important policy implications as school physical education classes and class time are being reduced.

Research has also suggested that physical activity may have less effect on cancer risk among population subgroups including obese individuals for some cancers.

While the physical activity guidelines recommend 30 minutes of moderate activity each day, they also suggest more is better. However, health promotion and behavioral science research has had only modest success at achieving sustained physical activity levels through intervention. We will review data on whether some benefit can be achieved at lower levels or how much greater the risk reduction may be at higher levels.

This is particularly important in light of research indicating that sedentary time is, independent of physical activity level, associated with an elevated risk of several cancers. Together, this data has pushed prevention messaging in the direction of “do something” instead of “do more.” While the risks of sedentary behavior are important, such messages may detract from research suggesting that for some cancers, such as prostate, participation in vigorous physical activity may be necessary to see a reduction in risk.

The benefits of physical activity for cancer prevention are well known. However, the message may need more refinement in light of emerging evidence on the timing, intensity and duration of activity necessary to reduce risk of specific cancers.

Citation Format: Kate Y. Wolin. Is it too late or too little? Prevention through physical activity. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr CN02-01.