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Tamoxifen, an anticancer drug, is given to treat breast
cancer. It also has proved effective when cancer has
spread to other parts of the body. Tamoxifen is most
effective in stopping the kind of breast cancer that
thrives on estrogen. Tamoxifen blocks the actions
of estrogen in a woman's body. Certain types of breast
cancer require estrogen to grow. Tamoxifen is also
prescribed to reduce the risk of invasive breast cancer
following surgery and radiation therapy for ductal
carcinoma in situ. The drug can also be used to reduce
the odds of breast cancer in women at high risk of
developing the disease. It does not completely eliminate
your chances, but in a five-year study of over 1,500
high-risk women, it slashed the number of cases by
44 percent.
Tamoxifen is a medicine that
blocks the effects of the estrogen hormone in the
body. It is used to treat breast cancer in women or
men.
It may also be used to treat other kinds of cancer,
as determined by your doctor. Tamoxifen also may be
used to reduce the risk of developing breast cancer
in women who have a high risk of developing breast
cancer.
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Celebrex relieves the pain and inflammation of osteoarthritis
and rheumatoid arthritis. It is the first of a new
class of nonsteroidal anti-inflammatory drugs (NSAIDs)
called "COX-2 inhibitors." Like older NSAIDs
such as Motrin and Naprosyn, Celebrex is believed
to fight pain and inflammation by inhibiting the effect
of a natural enzyme called COX-2. Unlike the older
medications, however, it does not interfere with a
similar substance, called COX-1, which exerts a protective
effect on the lining of the stomach. Celebrex is therefore
less likely to cause the bleeding and ulcers that
sometimes accompany sustained use of the older NSAIDs.
Celebrex has also been found to reduce the number
of colorectal polyps (growths in the wall of the lower
intestine and rectum) in people who suffer from the
condition called familial adenomatous polyposis (FAP),
an inherited tendency to develop large numbers of
colorectal polyps that eventually become cancerous.
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Toremifene citrate belongs to the general group of
drugs known as anti-hormones. It is used to treat
advanced breast cancer, and may be used with other
medicines to treat other cancers.
Toremifene citrate blocks estrogen. The cancer cells
which depend on estrogen to divide, stop growing and
die.
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Oncology Department, Hospital
Universitario, Madrid, Spain.
Lung cancer is an aggressive disease
that is the leading cause of death from cancer in
both males and females. Non-small cell lung cancer
accounts for approximately 75% of all cases of lung
cancer, and of these about 75% have locally advanced
or disseminated disease. Most patients diagnosed with
non-small cell lung cancer do not survive more than
2 years. Although chemotherapy has been shown to control
symptoms and improve quality of life, there remains
no standard, optimal chemotherapy regimen for non-small
cell lung cancer. Regardless of regimen and chemotherapy
agents administered, clinical trials have demonstrated
response rates of 20% to 30%, median survival times
between 35 and 40 weeks, and 1-year survival rates
of 20% to 25%. Because traditional chemotherapy regimens
have not shown substantial promise, new strategies
are being explored for the treatment of lung cancer,
including overcoming drug resistance, the use of antimetastatic
and antiangiogenesis drugs, drugs that target novel
molecular markers, signal transduction modulators,
gene therapy, and vaccines. There are few but exciting
new developments that may signal a more promising
future for patients with lung cancer.
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Arizona Cancer Center,
Tucson 85719, USA.
The multistep process of carcinogenesis,
which can take many years, provides many opportunities
for intervention to inhibit disease progression. Effective
chemoprevention agents may reduce the risk of cancer
by inhibiting the initiation stage of carcinoma through
induction of apoptosis or DNA repair in cells harboring
mutations, or they may act to prevent promotion of
tumor growth. Similarly, chemoprevention may entail
blocking cancer progression to an invasive phenotype.
Over the past decade, in vitro, preclinical, and clinical
data have supported the hypothesis that cyclooxygenase
(COX)-2 plays a central role in oncogenesis and that
treatment with COX-2 inhibitors offers an effective
chemoprevention strategy, as exemplified by the activity
of Celecoxib (Celebrex) in familial adenomatous polyposis.
These COX-2 data have contributed to initiation of
clinical trials testing COX-2 inhibitors for the chemoprevention
of a wide variety of cancers that overexpress COX-2.
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A number of established prescription drugs
are being tested to see if they have useful anti-cancer
effects. Some groups of people might consider taking such
"chemopreventive" drugs for prophylactic purposes,
even if they are not ill. Some drugs have produced promising
results; but they do all have side-effects. The concept
of "chemoprevention" is best known in the case
of preventing heart disease, for example drugs used to lower
blood-cholesterol levels or to lower hypertension.
Up to now, the emphasis in cancer research
has been on curing the condition. While these efforts continue,
an increasing number of researchers are searching for drugs
or other supplements that will prevent or delay the onset
of cancer in the first place. Because of the side-effects,
this is not recommended for everybody; but two developments
now make the preventive approach using drugs more attractive.
It is now recognised that many cancers start out years earlier
as pre-malignant lesions, which in principle may be diagnosed.
Second, there is growing evidence of a genetic link to many
types of cancer, and this again enables at-risk groups of
people to be identified.
More than 50 clinical trials are underway,
testing various compounds and drugs for anti-cancer action.
A study published early in 2003 demonstrated that low doses
of aspirin can prevent development of pre-cancerous polyps
in persons with a family history of colon cancer. A large
study is currently underway which is testing whether selenium
and vitamin E supplementation can prevent prostate cancer.
Another investigation is testing the anti-inflammatory
drug Celebrex, used originally to treat arthritis. This
has already been shown to reduce pre-cancerous polyps in
patients with a rare genetic syndrome that causes colon
cancer. Now studies are evaluating whether it will also
help protect against the formation of such polyps in average
individuals.
But the use of chemopreventive drugs is
controversial. This is partly because it is harder to pinpoint
who would most benefit from the treatment -- and thus weigh
against the potential risks. In the case of treating known
disease, this decision is much clearer. Thus cancer prevention
has usually focused on diet and lifestyle changes, rather
than using drugs. But for some people, particularly those
with an unfavorable genetic predisposition, such changes
may not be enough.
However, it should be pointed out that
some previous chemoprevention trials have produced unexpected
negative or confusing results. Some years ago the vitamin-A
precursor Beta-carotene seemed promising as a treatment
to reduce the risk of lung cancer. But trials on heavy smokers
showed that those taking this supplement actually got cancer
at a higher rate than the control group. Another not totally
encouraging example is the use of Finsteride to prevent
prostate cancer. In the trial, this drug clearly did reduce
the risk of getting prostate cancer. But the reported side-effects
included decreases in libido and potency, and, more worryingly,
those who did get cancer appeared to have a higher risk
of getting it in more severe form. More research is needed
to understand this effect.
A landmark study by the American
Association for Cancer Research, published in 2002, concludes
that many cancers start as pre-malignant lesions, that over
time develop into cancer. Many specialists argue that by
treating these lesions with drugs, the process by which
they become cancerous can be halted or at least delayed.
Finding these lesions is not so simple as measuring high
blood-cholesterol or hypertension; but screening techniques
are constantly advancing, and an aging population is becoming
more accustomed to regular health-screening tests. Treating
"pre-cancer" will probably be an increasing focus
of cancer-prevention efforts.
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