About 40 percent of Americans will experience a cancer diagnosis at some point in their lives, according to the most recent data from the National Cancer Institute. Different cancers have been linked to different causes, including genetics, unhealthy lifestyle choices such as inactivity and poor diet, obesity and environmental pollutants. When it comes to preventing cancer, no magic bullet exists. Research indicates, however, that certain measures, such as regular exercise, have been linked to a reduced risk of certain cancers. While no guarantees exist, living a healthier life can help stack the odds in your favor.
How Exercise Prevents Cancer
The exact mechanisms through which exercise prevents cancer have not been pinpointed. According to the University of Iowa Hospitals and Clinics, exercise might help reduce cancer risk on several fronts; it helps combat obesity, keeps hormone levels normal and speeds passage of cancer-causing toxins through the intestine, all of which can influence various types of cancer. This of course does not represent an exhaustive list of the cancer-preventing benefits.
Overall Cancer Risk
A Finnish study published in the July 2009 issue of the "British Journal of Sports Medicine" found that at least 30 minutes of intense exercise daily was linked with a 50 percent reduced risk of developing any type of cancer. The study tracked the exercise habits of over 2,500 men over the course of 17 years. Jogging was the most strenuous exercise recorded, fishing the least. While regular exercise was linked with reducing the development of any type of cancer, this study found it was particularly protective against cancers of the gastrointestinal tract and the lung.
Female Cancers
Research looking at the effects of exercise on reducing breast and endometrial cancer risk has found a positive association. According to the National Cancer Institute, over 60 studies from around the world have found exercise reduces the risk of breast cancer though the amount of reduced risk has varied widely between them -- anywhere from 20 to 80 percent. While the benefit appears to extend to pre and post-menopausal women, living an active lifestyle starting in your younger years might offer the greatest protection. Women with a healthier body weight -- a BMI under 25 -- appear to receive a greater level of protection than overweight women. A study presented at the 2010 American Association for Cancer Research Frontiers in Cancer Prevention Research Conference found that women who exercised at least 150 minutes a week were less likely to develop endometrial cancer, regardless of their weight. Having a BMI under 25 however, was associated with a 73 percent reduced risk while heavier women had a 52 percent reduced risk.
The University of Iowa says exercise has also been linked to a reduced risk of uterine cancer.
Cancers of the Lung, Prostate and Colon
The National Cancer Institute also notes research has demonstrated exercise helps reduce the risk of cancers of the colon, lung and prostate. As for colon cancer, the more vigorous the activity, the greater protection exercise affords, regardless of your weight. Various studies have demonstrated a reduced risk of 30 to 40 percent. Exercise appears to reduce lung cancer risk by about 20 percent but these benefits have been demonstrated more clearly for men than women. As for prostate cancer, research has not shown a strong association between exercise and reduced risk but the NCI does say that it has been shown to reduce the progression of the disease.
Considerations
These studies indicate that you should shoot for a minimum of 30 minutes of moderately-intense activity daily to reap the maximum cancer-prevention benefits. Like most healthy habits, they tend to work best in combination with other ones, rather than in isolation. Data presented at the American Association for Cancer Research's 2008 convention found that sleeping less than 7 hours a night negated the protective effects of exercise against cancer in women.
References
- National Cancer Institute: Physical Activity and Cancer
- New York Times: Does Exercise Reduce Your Cancer Risk?
- Science Daily: Exercise and Rest Can Reduce Cancer Risk
- University of Iowa: Exercise and Cancer Prevention
- Science Daily: Exercise May Reduce Risk of Endometrial Cancer
- National Cancer Institute: SEER Stat Fact Sheets: All Sites
