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LE Magazine November 2002
Aspirin
fights colon, prostate and pancreatic cancer
Earlier this year, the U.S. Preventive Services Task Force
recommended aspirin for the prevention of heart attack and
stroke. Further, it may not be long before doctors are
officially told to start advising patients with an elevated
risk of certain cancers to take aspirin daily, thanks to
recent findings.
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Research from Dartmouth Medical School presented at this
year’s meeting of the American Association for Cancer
Research, in San Francisco, showed that a daily dose of baby
aspirin lowered the risk of recurrent colon polyps. Of men and
women who had polyps removed, results from a follow-up
screening three years later demonstrated that new polyps had
developed in only 38% of low-dose aspirin users versus 45% of
those taking full-dose aspirin and 47% of a placebo group.
Meanwhile, The Mayo Clinic found that NSAIDs (non-steroidal
anti-inflammatory drugs), including aspirin and ibuprofen,
could reduce prostate cancer risk in men over age 60 by
two-thirds [Mayo Clin Proc.
2002;77:219-225]. After tracking more than 1300 men for 5.5
years, researchers found that only 23 NSAID users developed
prostate cancer compared to 68 non-users; the benefit also
increased with age. The latest findings, from the University
of Minnesota, reveal that aspirin may also reduce the risk of
pancreatic cancer [JNCI 2002
Aug 7;94(15):1168-1171]. Researchers analyzed aspirin and
other NSAID use in over 28,000 postmenopausal women, and
discovered that aspirin users had a 43% lower rate of
pancreatic cancer than non-users, and that risk reduction
increased proportionally to frequency of use. Researchers,
however, will contain their enthusiasm about aspirin for
cancer prevention, until they weigh all the benefits and risks
related to regular aspirin use.
—Angela
Pirisi
Low
antioxidant levels may contribute to hepatitis C
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It is believed that oxidative stress may play a role in the
pathogenesis of viral hepatitis C. Higher rates of lipid
peroxidation and lower antioxidant levels, as measured in
blood and urine samples, have been noted in the advanced
stages of this disease. However, some findings now suggest
that damaging oxidative stress may occur much sooner than when
disease complications appear (i.e. cirrhosis), and may
actually contribute to them. A recent UK study of 42 chronic
hepatitis C patients, for example, showed that a lipid
peroxidation marker (8-isoprostane) and the ratio of oxidized
to reduced glutathione were significantly elevated in both
cirrhotic and non-cirrhotic patients [J Hepatol 2002 Jun;36(6):805-11].
Furthermore, antioxidants, including glutathione, selenium and
vitamins A, C and E, were significantly decreased compared to
controls. The authors concluded that, “Antioxidant
therapy may therefore have a role in slowing disease
progression to cirrhosis.”
Other researchers have demonstrated a high rate of
glutathione turnover in the lymphocytes of hepatitis C
patients, which may alter lymphocyte function and facilitate
chronic infection [J Hepatol
1999 Nov;31(5):808-14]. Some have found that children with
chronic viral hepatitis B and C have significantly lower
catalase (CAT) and superoxide dismutase (SOD) activity, and
higher glutathione peroxidase (GSH-Px) activity than
non-infected children, hinting at compromised antioxidant
defenses [Med Sci Monit 2000
Jul-Aug;6(4):713-8]. One theory is that hepatitis C viral
proteins (i.e. NS5A) may be what induce oxidative stress
[Proc Natl Acad Sci USA 2001
Aug 14;98 (17):9599-604], by upsetting intracellular calcium,
thus triggering a jump in reactive oxygen species (ROS) in
mitochondria, and activating NF-kappaB and STAT-3
transcription factors.
—AP
Heart disease
risk and abdominal fat
Abdominal fat, or visceral fat, has been associated with
hypertension, diabetes and cardiovascular disease. Now a new
study that looked at a European sample of middle-aged men
confirms that abdominal fat is an independent risk factor for
heart attack. Body measurements were taken from 1346 healthy
Finnish men, aged 42 to 60, to assess their waist-to-hip
ratio. Results revealed that, over a 10-year period, those
with the highest ratio had nearly three times the risk of
heart attack or related coronary events than men with lower
ratios [European Heart
Journal 2002;23:706-713].
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Earlier studies had shown this to be true in men and women
[Int J Obes Relat Metab
Disord 1999 Jan;23(1):90-7]. In Paris, investigators
found that, among 552 men and 160 women at risk for
cardiovascular disease, aged 30 to 74, the risks of a coronary
event over the next 10 years and a heart attack over the next
six years was highest in those with the highest
waist-hip-ratio. Meanwhile, data from the Nurses’ Health
Study [JAMA 1998 Dec
2;280(21):1843-8] showed that a higher waist-to-hip ratio and
waist circumference were independently and strongly related to
heart disease risk, even among women with a body mass index of
25 kg/m2 or less.
Other research has shown that visceral fat breeds insulin
resistance, which can lead to type 2 diabetes. As study
results presented at the this year’s American Diabetes
Association’s annual meeting suggest, abdominal fat may
be responsible for creating abnormal glucose metabolism by
releasing fatty acids into the bloodstream, which then
overstimulate the liver’s production of glucose.
Abdominal fat has also been associated with increasing
vascular stiffness, leading to high blood pressure and its
complications, such as heart disease [Hypertension 2001
Sep;38(3):429-33].
—AP
Pain killer
or cancer treatment?
What a pleasant surprise it was when scientists established
that the humble pain killer, aspirin, can be used as a potent
weapon against heart attack, stroke and some forms of cancer.
Now a related type of painkiller, cyclooxygenase (COX-2)
inhibitors—nonsteroidal anti-inflammatory drugs that
block the COX-2 enzyme—have joined the ranks of
disease-fighting drugs.
The latest evidence points to COX-2 inhibitors to help
treat an aggressive form of lung cancer in its early stages.
Findings from Cornell University scientists presented at the
American Society of Clinical Oncology meeting in Orlando,
Florida in May were that administering 400 mg of a COX-2
inhibitor called Celebrex twice daily along with chemotherapy
treatment for six weeks helped fight raging lung cancer. Among
16 patients treated, the cancer virtually disappeared in five
of them, tumors shrank in five patients, and the disease
stabilized in four others. In a third of the patients, they
found cancer cell death when their lung tissue was examined
under a microscope. The authors suggest, however, that a
larger placebo-controlled study will be needed to compare the
effects of chemotherapy plus Celebrex to chemotherapy
alone.
COX-2 produces an inflammatory, hormone-like byproduct
called prostaglandin, which is part of the body’s natural
response to injury. In cancer cells, COX-2 is often
overexpressed, which leads to the overproduction of
prostaglandins. The latter supply blood to cancer cells for
growth, keep the immune system from attacking them, and reduce
the rate of cancer cell death by setting their internal killer
switch to off. COX-2 inhibitors and NSAIDs in general have
already been eyed for the prevention of certain cancers, such
as colon and breast. Life Extension has recommended COX-2
inhibitors for cancer treatment since 1996.
—AP
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