Lifestyle therapy for prostate cancer: Does it work?
Prostate cancer is the most common internal malignancy in American men;
it’s second only to lung cancer among the leading causes of male
cancer deaths. That makes it an urgent problem, and it is finally getting
the scientific respect it deserves. Still, despite thorough investigations
that have yielded major advances, many aspects of the disease remain
One area of uncertainty is the cause of prostate cancer. Genetics certainly
play an important role, but heredity cannot explain most cases. Lifestyle
factors have also been implicated; the leading candidate is diet. A high
consumption of saturated fat from animal sources is linked to an increased
risk of prostate cancer, while whole grains, tomatoes, some vegetables,
fish, and soy appear protective. Other lifestyle elements that have been
linked to the disease include obesity, lack of exercise, and heavy smoking
Another area of uncertainty is the best treatment. At one extreme, the
evidence favors surgery for men with moderate- to high-grade tumors.
At the other extreme, men with low-grade tumors might be best served
by watchful waiting. But many men with early, localized prostate cancer
fall between these extremes.
Faced with these uncertainties, it is not surprising that up to 73%
of men with prostate cancer take nonprescription supplements, and smaller
numbers use diet, exercise, or both in the hope of improving their outcome.
Most of these men also receive conventional therapy, but a few depend
on lifestyle alone.
The appeal of lifestyle therapy is obvious — but does it work?
Experts don’t know, though a study raises hope that it may have
a beneficial impact.
Designing a trial
Scientists from five American research centers joined forces to study
lifestyle therapy for prostate cancer. The trial, conducted in San Francisco,
was headed by Dr. Dean Ornish, a nutrition expert, and Dr. Peter Carroll,
a noted urologist.
One challenge was to design a program that was intensive but sustainable.
It included four elements:
Diet. Based on Dr. Ornish’s ultra-low-fat vegan
diet that is sometimes used for heart disease, the regimen provided less
than 10% of calories from fat and contained only trace amounts of cholesterol.
The menu consisted mainly of fruits, vegetables, whole grain products,
legumes, and soy products.
Supplements. Each man took 58 grams of powdered soy
protein, 3 grams of fish oil, 400 IU of vitamin E, 2 grams of vitamin
C, and 200 micrograms of selenium every day.
Exercise. The men walked for 30 minutes at a moderate
pace six days a week.
Stress reduction. The men performed yoga-based stretching,
breathing, meditation, and relaxation exercises for a total of an hour
The trial lasted one year. Three members of the lifestyle treatment
group dropped out because the program was too arduous, but none left
because they required conventional therapy. Six members of the control
group required conventional therapy during the year because of the progression
of their disease.
Initially, the treatment and control groups had identical PSA levels.
At the end of the year, a small but significant difference was evident.
And tests of how the men’s blood affected the growth of prostate
cancer cells showed similar changes. Blood samples from the lifestyle
treatment group inhibited prostate cancer cell growth by 70%, while samples
from the control group inhibited growth by only 9%.
The intensive lifestyle study did not answer the $64,000 question: Can
this program improve a man’s outlook? Since all the men had early-stage,
less aggressive tumors, the cancers would be unlikely to grow fast enough
to demonstrate clinical differences in just a year. The scientists are
continuing to track the men to see if other differences in symptoms or
survival emerge over time. After just a year, though, the trends in PSA
levels and cancer cell growth inhibition raise hope that lifestyle treatment
may prove helpful.
Although the intensive lifestyle trial was careful and scientifically
rigorous, it is only one study. But other investigations, though smaller
and shorter, tend to support the possibility that lifestyle changes may
slow the growth of prostate cancer cells.
A large body of evidence suggests that lifestyle factors have a powerful
influence on a man’s risk of prostate cancer. Much more research
is needed before lifestyle therapy can be recommended clinically. And
even if these changes prove beneficial, they will add to but not replace
Since regular exercise, stress reduction, and a low-fat, high-fiber,
plant-based diet are good for general health, they will make a reasonable
addition to any prostate cancer program.
Lifestyle therapy or conventional treatment? For prostate cancer, as
for so many areas of health, it’s not a question of “either/or” but
an answer of “both.”
August 2007 update
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