From OncoLog, July 2012, Vol. 57,
House Call: Exercise and Cancer Prevention
Benefits of exercise apply to a variety of cancers
People who engage in regular, moderate exercise are less likely to
develop some forms of cancer than are people who do not exercise
regularly, according to recent studies. The evidence is strongest for
colon, endometrial, and postmenopausal breast cancers.
Connecting the dots
“Although the connections between exercise and cancer prevention are
not entirely clear yet, there are some probable explanations,” said
Karen Basen-Engquist, Ph.D., a professor in the Department of
Behavioral Science at The University of Texas MD Anderson Cancer
Center. One explanation relates to weight control. Regular exercise can
prevent obesity, which is associated with many types of cancer. Obesity
can cause the body to produce too much estrogen, which is a factor in
some cancers, such as breast cancer. Obesity can also cause the body to
produce too much insulin. Excess insulin can lead to the overproduction
of cells, which, in turn, can lead to cancer.
Physical activity may also prevent cancer in other ways. It can boost
the immune system and reduce inflammation; these help the body fight
cancer development. Exercise also speeds the passage of food through
the digestive system, possibly reducing how long cancer-causing
substances spend in the colon. Finally, exercise can help regulate cell
death (a normal process), preventing the uncontrolled growth associated
Getting enough exercise
The American Institute for Cancer Research recommends that people get
at least 30 minutes of moderate physical activity every day; 60 minutes
of daily activity is even more beneficial. Anything that gets your
heart beating more quickly and makes you breathe more deeply can count
as moderate exercise. Participating in a mix of strength training and
cardiovascular activities, such as jogging or brisk walking, will help
you get the most out of exercise. Although studies have suggested that
incidental or occupational activities such as taking the stairs may
have some benefits, the cancer prevention benefits of deliberate
exercise are much clearer.
If you find the prospect of 30 minutes of sustained exercise daunting,
take heart: researchers have found that breaking those 30 minutes into
smaller blocks of time can be just as beneficial.
Dr. Basen-Engquist suggested several ways to ease the transition into
regular exercise. Before starting out, think about the kinds of
activities you enjoy. These might be things you don’t traditionally
think of as exercise—dancing or walking the dog. If you start with
something you enjoy, your exercise program is more likely to last.
Start slowly and work your way up. Don’t be disappointed if you’re not
exercising 30 minutes every day from the outset. And for support, look
to friends or other groups who also participate in the physical
activities you enjoy.
Dr. Basen-Engquist offered three principles for maintaining the
motivation to exercise: setting goals, monitoring progress, and
rewarding yourself. Your goal might be to increase the distance you
cover, the time you spend exercising, or your repetitions of an
activity (such as laps of the pool).
A range of devices allow you to monitor your progress. Wearing a
pedometer will allow you to count your steps both during exercise and
throughout the day. You might also time your exercise sessions, adding
them up at the end of the month and aiming for longer sessions in the
next month. New applications for smart phones and Web sites such as
MapMyRun.com can help measure distances and speed. If you would rather
keep things simple, you might chart your progress on a calendar, where
you can also set new targets for speed, distance, calories burned, or
For rewards, you might try fruits such as berries. Dr. Basen-Engquist
suggested allowing yourself to download a new song or buy some new
reading materials if you meet your goals. And by only allowing yourself
to engage in a certain fun activity (perhaps reading a favorite
magazine) while exercising, you’ll come to associate exercise with
enjoyment instead of self-denial.
Vacations, bad weather, and other disruptions to your routine can
derail your exercise plans. So, if your exercise program is going well
but you see a high-risk situation ahead, take preventive action: pack
your exercise clothes for a vacation, or have an indoor activity in
mind for days when the outdoors look unappealing.
Even though the mechanisms that connect exercise with cancer prevention
are not well understood, Dr. Basen-Engquist said, “You can confidently
say that being active will benefit your health more than being
– A. Scholtz
For more information, talk to your physician, visit www.mdanderson.org, or call askMDAnderson at 877-632-6789.
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