|
Reducing Breast
Cancer Risk: Which Steps Are Best?
Since there are several types
of breast cancer, we shouldn’t be surprised at how challenging
it is for researchers to identify which steps can most effectively
reduce risk. Study results vary about the impact of vegetables,
fruits, whole grains, total fat and different types of fat.
However, the American Institute for Cancer Research (AICR) recently
published an update to its 2007 expert report looking at lifestyle
and breast cancer risk. This is the largest review of research
on this topic ever conducted and has confirmed that weight control,
regular physical activity and limitation of alcohol are the foundations
of a lifestyle to lower breast cancer risk.
A Healthy Weight: The landmark
2007 report and now the update conclude that overweight convincingly
increases risk of postmenopausal breast cancer. As a woman’s
body weight increases so does her risk and excess body fat at
the waist may be specifically tied to postmenopausal breast cancer
risk.
A 2009 review of research on
postmenopausal breast cancer in the Journal of the National Cancer
Institute also identifies weight control as one of the most important
steps to reduce risk. Nine large population studies linked adult
weight gain of 22 to 44 pounds with up to a 50 percent increase
in risk, and gains above that are linked with a 45 to 87 percent
increase in risk. |
|
Greater body fat seems to increase
body levels of estrogen after menopause, which explains its link
to estrogen-sensitive breast cancer. Increased body fat also
leads to increased levels of insulin and insulin-like growth
factors, increasing risk of even estrogen-negative breast cancer.
Physical Activity: The AICR report
convincingly links regular physical activity to lower risk of
postmenopausal and probably of pre-menopausal breast cancer as
well. In their analysis of multiple studies researchers found
that two hours of moderate physical activity each week will begin
to decrease postmenopausal breast cancer risk. The JNCI review
notes that in several large studies, women with the highest physical
activity levels show 14 to 20 percent lower breast cancer risk
than those least physically active.
Physical activity potentially
protects against breast cancer through strengthening the immune
system as well as reducing levels of both reproductive and insulin-related
hormones, and through its impact on weight control. There is
no question that activity matters, rather, the question is how
much and what types provide optimal protection. A minimum of
thirty minutes a day of moderate activity is the current overall
health recommendation.
Limiting Alcohol: According to
the AICR report, limiting alcohol is the step that most clearly
reduces risk of both pre- and postmenopausal breast cancer.
Combined analysis of many studies consistently shows a 5 to 10
percent increase in breast cancer risk with each daily standard
alcoholic drink. One such drink equals 12 ounces of beer, 5
ounces of wine or one-and-a-half ounces of 80-proof liquor.
One analysis in the JNCI review showed that among postmenopausal
women, those who drink alcohol show a greater risk than those
who drink no alcohol.
One more step that clearly reduces
risk of pre- and postmenopausal breast cancer: breastfeeding.
Beyond these four links, the answers get much less clear. The
JNCI review of research concludes that women can reduce their
risk of postmenopausal breast cancer with a low fat diet. However,
the AICR report showed some indication that total dietary fat
may be associated with increased risk, but more research is needed.
Eating plenty of vegetables,
fruits, whole grains and beans is clearly recommended for overall
health, but unless the low calorie content of these foods is
used to support a healthy weight, research is inconsistent about
any direct breast cancer protection. However, researchers are
studying whether benefits may vary with particular foods or personal
genetic differences. |
Print
Forums
Refer Page
