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New Reports
on Physical Activity and
Breast Cancer Prevention
New research is adding more insight
into the link between walking and other forms of physical activity
and lower risk of breast cancer. A landmark report on diet, activity
and the prevention of cancer from the American Institute for
Cancer Research (AICR) noted that increased physical activity
probably lowers risk of postmenopausal breast cancer and potentially
risk of pre-menopausal breast cancer as well. This week, I’ll
share some of the most-commonly asked questions regarding cancer
and physical activity:
Is it too late to make a difference
after years of sedentary living? Research
suggests that it’s never too late to start making changes
to reduce your cancer risk. In one recent Japanese study, the
most active women had less than half the risk of postmenopausal
breast cancer than the least active women. Study participants
were 40 to 69 years old at the start of the study. In another
recent study from Germany, physical activity after age 50 showed
an even stronger effect in reducing risk of postmenopausal breast
cancer than physical activity at ages 30 to 49. |
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Is being active worth it if
I don’t lose weight? While
many people connect exercise to weight control, physical activity
protects our health in many ways. Recent studies support findings
that physical activity helps lower postmenopausal breast cancer
risk both through assisting weight control and more directly.
Though studies are not universally consistent, in both studies
noted above, the link between more activity and less breast cancer
was independent of weight loss.
How much activity will it
take? Here’s where
it gets harder to interpret because studies measure and categorize
activity level in different ways. In the Japanese study mentioned
above, women needed to accrue at least one hour of walking daily
plus at least one hour of other exercise each week before they
showed a significantly lower risk. In the German study, a 21
to 25 percent lower risk of postmenopausal breast cancer was
seen in women who got the most leisure time physical activity
– the equivalent of at least two hours a day of brisk walking.
Although these recent studies don’t show a clear decreased
risk of breast cancer until you reach an hour or more of daily
activity, other analyses reveal that even modest activity can
impact risk. The AICR second expert report shows that risk of
postmenopausal breast cancer drops by three percent for the equivalent
of about two hours of moderate walking weekly. A previous analysis
of 48 studies looking at risk of pre- and post-menopausal breast
cancer showed a 12 percent drop in risk with two hours of moderate
exercise weekly. And an important reminder: If you can’t
find a large block of time in your week, the same benefits are
seen when activity is broken up into 10- or 15-minute blocks
of time.
Is more intense activity better?
Several studies, including
the Japanese study discussed here, show added protection from
breast cancer when women include at least some vigorous activity
like jogging, hill walking or aerobics classes each week.
We clearly need more research
to resolve some of the more detailed questions about activity
and breast cancer risk. But meanwhile, health experts acknowledge
that the payoffs of regular physical activity are substantial.
And as you begin to discover just how good it makes you feel,
don’t hold back, because the more, the better (within reason). |
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