How exercise can affect your cancer risk

This is the second of a two part post discussing cancer risks.  Part one, discussing the diet's influence on cancer risk can be found here. This time we will discuss how exercise can affect risk and survival of cancer.  Again, this information is my medicalese translation of information from the American College of Sports Medicine's Guide to Exercise and Cancersurviorship.  There is quite a bit of information suggesting that there are positive benefits both for preventing and surviving colon, breast, and prostrate cancers. For the purpose of this discussion, if a person were to rate intensity of exercise on a scale of 1-10; one would be so light a person could take a nap and ten would be so intense that to exercise harder might literally kill a person.  Light activity will also refer to a time commitment of less than three hours per week and/or rating of 2-4 in intensity; moderate activity three to six hours per week and/or a rating of 5-7; and vigorous activity as being more than six hours per week and/or an intensity rating of 8 or higher.

It is most evident that exercise can help prevent colon cancer.  Even light activity may reduce the occurrence of colon cancer by 25-30% over inactive people.  One study in particular showed that people who exercised vigorously may reduce risk of occurrence up 49%.  It has been noted that for both prevention of and reducing risk of reoccurence, it is best to engage in 30-60 minutes of moderate to vigorous activity per day is best.  It also would appear that those who engage in a lifetime of physical activity are at the lowest risk of colon cancer as it is less common in people who maintain a healthy body weight through a combination of diet and regular activity.  It would seem that regularly moving keeps a person, well, regularly moving.  The more frequent the bowel movements the lower the risk of colon cancer.

Thanks to the efforts of the Susan B Komen foundation, breast cancer is probably the best promoted form of cancer that can be prevented from regular exercise or see a decreased risk of reoccurence and an increased survivor rate.  A review of 73 studies found that on average, physically active women were 25% less likely to develop breast cancer than inactive women.  Again, the more physically active a women is the less likely she is to develop breast cancer.  This is especially true of women who have remained physically active throughout their lives or post-menopause.   In fact, one study has shown that fatality of breast cancer drops by 51% for post-menopausal women. It has also been shown that reoccurence rates were decreased by up to 30% for women who remained physically active for three years or more after diagnosis.


Prostrate cancer is another cancer with some, but not much, information about the effect of exercise.  Of the studies done about one-third show a positive effect of exercise on reducing risk and increasing survival.  Light-to-moderately active men seem to be about 10% less likely to develop prostrate cancer.  The main connection hear is that men with healthy BMIs (a healthy weight to height ratio) are less likely than overweight or obese men to develop it.  One problem that was mentioned in regards to studying exercise effects on prostrate cancer is that compared with other types of cancer; prostrate cancer exhibits fewer obvious signs and symptoms that it exists.  Because of this it is more likely for a man with prostrate cancer to die without diagnosis than from other types of cancer.  This seems to also be influenced by the fact that healthier, active men are more likely to be screened and have prostrate cancer detected in than inactive men. For this reason the accuracy of the numbers of physically active men and prostrate cancer being fatal may not be an accurate representation of the general population.  In other words, exercise probably does more to prevent prostrate cancer than current research can show because healthier men are more likely to get screened.  This may mean that healthier men look like they have a higher risk of fatal prostrate cancer than they actually do when compared the numbers of unhealthy, inactive men diagnosed and those that die before being diagnosed.

In summary, although it is not conclusive, there are strong links that indicate that those who engage in regular exercise are less likely to develop several types of cancer.  If the cancer does develop, people who are active on a regular basis are more likely to survive and avoid reoccurence.  The more exercise is done and the more intense the exercise the better the chances of minimizing the risk of cancer.