Excerpt from: "Mythbusters: Complementary and Alternative
Treatments in Cancer" (Medscape)
Exercise
Proposition: Engaging in physical activity, such as walking, running
or recreational sports, can improve cancer survival.
What
the science says: The benefits of exercise for both mental and physical health
cannot be denied. Since 1996, the Centers for Disease Control and Prevention
has recommended that adults engage in moderate-intensity activities, such as a
brisk walk or jog, for at least 30 minutes 5 days a week.[4] In 2008, the American Cancer Society (ACS) reiterated these
recommendations, providing a wealth of new evidence to support the role of
exercise in cancer prevention and for promoting overall health.[5]
A
growing body of research now suggests that exercise may not only help protect
people from developing cancer but also may increase survival in those already
diagnosed.[6] A 2005 prospective, observational study, which followed almost
3000 women diagnosed with nonmetastatic breast cancer, found that those who
engaged in moderate physical activity -- equivalent to walking 3-5 hours each
week at a modest pace -- significantly lowered their risk of dying from breast
cancer compared with their more sedentary peers.[7]
Exercise
may also enhance survival for those diagnosed with nonmetastatic colorectal
cancer.[8] In one observational study which followed 573 women diagnosed
with stage I, II, or III colorectal cancer, those who were physically active
after their diagnosis, regardless of their prediagnosis exercise regimen, were
less likely to die from cancer or in general. And the more exercise they did,
the better their odds became: Those who engaged in 6 or more hours of moderate
exercise each week, including walking, bicycling, swimming, and running,
reduced their risk of dying from cancer by about half compared with their peers
who exercised less than 1 hour per week.
For men
with prostate cancer, the data also look
promising. In a prospective study, which followed 47,620 men in the United
States over 14 years, researchers from Harvard School of Public Health analyzed
the relationship between cancer incidence and reported physical activity
levels.[9] Although the researchers did not find an association between
exercise and survival in younger men, in men 65 years and older, regular
vigorous activity did appear to slow the progression of both advanced and fatal
prostate cancer. The authors concluded that "regular vigorous activity
could slow the progression of prostate cancer and might be recommended to
reduce mortality from prostate cancer."
Encouraging
results from a 2014 prospective cohort study showed an association between
exercise and survival in men diagnosed with a range of cancers.[10] The study followed 1021 men diagnosed with cancer for 2 decades,
in which time the men completed questionnaires about their level of physical
activity. Those who engaged in more frequent and vigorous exercise, measured by
their estimated weekly calorie burn, had the lowest risk of dying from cancer.
The best survival advantage occurred in men who burned over 3000 calories per
week, which is equivalent to about 45 minutes to an hour of hiking or jogging 5
days a week for a typical 150- to 200-lb man.
What
the expert says: According to Dr. Deng, "Physical activity is the only
integrative oncology therapy with a survival advantage."
Cheryl
L. Rock, PhD, RD, a professor in the Department of Family and Preventive
Medicine at the University of California, San Diego, added, "Exercising
not only lowers a person's risk of developing cancer and makes it less likely
they will have a recurrence, but it also increases the odds of cancer survival.
For patients diagnosed with cancer, exercise enhances quality of life and can
change how the body metabolizes food, which may promote important healing
processes."
As an
oncologist who practices integrative oncology, Dr. Rosenthal tries to get
patients to increase their activity levels to at least 30 minutes a day, 5 days
a week. "Although the specific type of exercise may vary, patients do need
to get their heart rate up, so the exercise should be higher-impact, such as
jogging, as opposed to stretching or yoga. Even on a bad day, doing just 5-10
minutes could have preventative and rehabilitative effects," he said. In
fact, Dr. Rosenthal noted, "at the Dana-Farber Cancer Center, we give
chemotherapy to some patients while they walk on a treadmill."
The
evidence supporting exercise in cancer care is so compelling that most experts
consider physical activity to be part of mainstream, not complementary,
treatment. "At this point, exercise and diet regimens can easily be
considered conventional medicine," said David Gorski, MD, PhD, a surgical
oncologist at the Barbara Ann Karmanos Cancer Institute in Detroit who specializes
in breast cancer surgery.
Despite
the clear benefits of physical activity, Dr. Deng cautioned, "We can't
give patients generic advice about exercising after they are diagnosed with
cancer. There are many nuances to developing an appropriate exercise program
that is tailored to patients' individual condition and needs -- one that takes
into account their personal preferences, whether they are overweight or
underweight, their current diet, their type and severity of cancer."
Verdict:
Confirmed. The evidence showing that regular moderate-to-vigorous exercise
improves survival for men and women diagnosed with a range of cancers is
compelling.
