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New Risk Factor for Stomach Cancer
Stomach cancer is one of
the "Top 10" causes of death from cancer for men in the United States
and is the leading cause of cancer death in many countries of the
world, especially in Asia. Dr W. You of the National Cancer Institute
(NIH) along with other researchers studied the cause of stomach
cancer in Linqu County, China where there is a very high rate of
death from stomach cancer. They studied people living in 14 different
villages; 3,433 people in all. They checked serum levels for micronutrient
intake, presence of antibodies for Helicobacter pylori (a bacteria
thought to cause ulcers), alcohol use, smoking, eating habits, and
performed endoscopic examinations (viewing the lining of the stomach.)
Four to five years later,
these careful examinations were made again. By actually viewing
the stomach with endoscopes, they could determine who had developed
gastric cancer or changes suggesting early development of cancer
and who didn't. Using this process they identified the primary risk
factors related to cancer development. They are:
The presence of H. pylori
infection at baseline increased risk by 80%. Cigarette smoking increased
risk by 40 to 60 percent. The longer someone had smoked the higher
the risk. Alcohol use raised the
risk moderately, 30 to 40 percent but not significantly.
On the other hand, those
who had a higher intake of vitamin C (top third vs. bottom third)
had 80 percent less risk of developing stomach cancer.
This is good news in that
all four of the risk factors identified can be eliminated or treated.
To reduce the risk of stomach cancer this study suggests avoiding
smoking and drinking, eating foods rich in vitamin C (more fresh
fruits and vegetables, especially citrus), and if you have an ulcer
or have antibodies for H. pylori, getting treatment to eliminate
this infection.
Reference: Journal of the National Cancer Institute,
Vol.92, no. 19, 1607-1612, Oct. 4, 2000
New Cause for Colorectal
Cancer Identified
Large population studies
have shown the Western lifestyle to be associated with a high risk
of colorectal cancer. In the U.S. colorectal cancer is the second
leading cause of death from cancer for both men and women.
Risk factors strongly related
to lifestyle include an energy rich diet high in refined carbohydrates
and calories, low levels of physical activity, and being overweight.
Until recently, however, there was little understanding of the connection
between these factors and colorectal cancer.
A new study adds good evidence
that may explain this relationship. It appears that high insulin
levels in the blood mediate the increased risk for colorectal cancer.
High insulin in turn affects bioactivity of insulin-like growth
factor (IGF) 1. IGF-1 affects cell proliferation and aptotic cell
death, the body's way of killing unwanted or abnormal cells including
cancer cells.
Research was conducted on
a group of 14,275 women who were enrolled in a diet and cancer prevention
study in New York. Eating and lifestyle habit data were gathered
along with blood testing to determine blood insulin levels. These
people were followed for six years to determine who would get colorectal
cancer.
Researchers found an increase
in colorectal cancer with higher levels of blood concentrations
of C-peptide, a marker for insulin secretion. The higher the insulin
levels the higher the rate of colorectal cancer. Women in the top
20 percent of insulin levels were 2.9 times more likely to get colorectal
cancer and 4.0 times more likely to get colon cancer than those
women in the bottom 20 percent (low insulin levels).
To help prevent colorectal
cancer, this study suggests that is important to lower fasting insulin
levels (reduce insulin resistance) by:
Being physically active.
Get 30+ minutes of physical activity daily. Eat unrefined foods. High fiber foods help lower blood
glucose and high insulin levels. Limit calorie intake to avoid obesity.
Obesity, especially fat in the abdominal area, increases insulin
resistance and increases risk for high blood insulin levels.
Reference: Journal of the National Cancer Institute,
Vol. 92, No. 19;1592-1600, Oct. 4, 2000
Strategies for Reducing
Risk for Breast Cancer
Breast cancer is a leading
cause of death for women. One in eight women will get breast cancer
sometime in their lifetime. The good news, however, is that much
can be done to prevent it or find it early while it is still treatable.
In a recent study of 44,788 pairs of twins to determine the role
inheritable factors played in the development of breast cancer,
it was found that only 27 percent of breast cancer was explained
by inheritable traits leaving over 70 percent caused by environment
or lifestyle factors1. That means that a large majority
of breast cancer cases could and should be preventable.
A quick review of breast
cancer risk factors2, 3 can help determine what strategies
are most helpful in reducing risk.
Age is a major factor. Risk climbs
quickly after age 50. Women over 50 are at 6.5 times greater risk
for breast cancer than women under the age of 50.
Family history. If you have one first
degree relative (mother, sister, daughter) who developed breast
cancer, your risk doubles. If you have two first degree relatives
your risk increases five-fold.
Age at first live birth. Women having
their first baby after the age of 30 Vs before age 20 have up to
twice the risk.
Early menarche. Risk increases 20
to 50 percent with menarche earlier than 12 years Vs 14 years or
older.
Late menopause. Menopause at age
55 or older Vs younger than 55 increases risk by 50 to 100 percent.
Hormone replacement therapy for
five or more years can increase risk slightly-in some studies up
to 50 percent.
All risk factors above,
other than age and family history, appear to be related to hormone
levels, factors we generally don't have a lot of control over. Lifestyle
factors associated with lower risk of breast cancer include:
Alcohol. One study showed that women
who have two or more drinks per day have a 40 percent increased
risk. The Nurses Health Study showed that even as little as ½ to
1 drink/day resulted in an increase in breast cancers.
Excess weight. Excess fat increases
risk, especially in women who gained 45 pounds or more since age
18.
Sedentary lifestyle. Regular physical
activity reduces risk of breast cancer. In the Nurses Health Study,
those women who got even as little as an hour of physical activity
a week reduced risk up to 20 percent.
Unhealthy diet. A large study of
42,031 women by the National Cancer Institute looked at diet and
cancer mortality. They found that the 25 percent of women who ate
the healthiest diet were 40 percent less likely to die from breast
cancer than the 25 percent of women who ate the least healthy diet4.
Numerous studies have found that a high
intake of fruit and vegetables is particularly protective against
breast and other cancers.
Everyone benefits from a
healthy lifestyle, but if you have one or more risk factors you
have the most to gain from adopting the prevention strategies listed
below.
Choose healthy foods high
in fruits, vegetables, unrefined grains, and low in animal fats
and refined calories. Engage in regular physical
activity such as brisk walking; 30 minutes-or more-each day is
ideal. Keep your weight in a
healthy range. If you are overweight, join a group that can help
you reach your objective. Avoid alcohol. If you
choose to drink, limit intake to special occasions. And as an added precaution,
get regular physical exams including a breast exam and mammograms
as recommended by your doctor. Mammograms are usually recommended
for all women starting at age 40 (sooner if there is high risk).
Don't forget to practice monthly self-breast exams.
For those women at very
high risk there is also a medication, Tamoxifen, that is now available
to reduce risk. In a clinical trial of 13,388 women followed for
four years, Tamoxifen reduced the odds of breast cancer by nearly
50 percent5. Tamoxifen was also found to help maintain
bone density in postmenopausal women. As with all drugs, however,
it does have side effects. If you are a high risk you may want to
discuss this option with your physician.
References:
1.The New England Journal of Medicine,
July 13, 2000;343:78-85.
2.The New England Journal of Medicine,
Feb. 24, 2000;342:564-571.
3.Harvard, Women's Health Watch, Oct. 2000.
4. Journal of the American Medical Association,
April 26, 2000;283:2109-2115
5. The New England Journal of Medicine,
July 20, 2000;343:191-196.
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