Treating Cancer Before It Starts
By Elizabeth Whittington
While exercise, a healthy diet and not smoking can reduce
cancer risk, high-risk individuals may be good candidates
for chemoprevention—using drugs or certain supplements
to further lower risk. Clinical trials have looked at various
risk-reduction methods for some common tumor types.
For the past two decades, women at high risk for breast cancer
were encouraged to take tamoxifen to lower their risk by half.
Unfortunately, because of the risk of life-threatening side
effects, including blood clots and endometrial cancer, many
high-risk women choose not to take the five-year treatment.
This year, a study comparing Evista® (raloxifene), an
osteoporosis drug, versus standard tamoxifen showed Evista
equaled tamoxifen’s effectiveness in preventing invasive
breast cancer. The makers of Evista plan to seek drug approval
for lowering breast cancer risk later this year.
more than 18,000 men, showed that a drug traditionally used
to treat prostate enlargement called Proscar® (finasteride)
lowered the risk of prostate cancer from 24 percent to 18
percent when taken for seven years. Proscar blocks an enzyme
called 5-alpha reductase type 2 that is needed to convert
testosterone to dihydrotestosterone (DHT), a male hormone
involved in promoting prostate cell growth. While Proscar
produced positive results in preventing some prostate cancers
during the trial, researchers noticed that men who did get
prostate cancer had more aggressive tumors. Researchers are
now examining whether Proscar caused the tumors to become
more aggressive or if the drug simply doesn’t work as
well on aggressive cancers.
A second-generation 5-alpha reductase inhibitor called Avodart®
(dutasteride) inhibits both enzyme type 1 and 2—a double
punch that reduces DHT production faster than Proscar. Final
results of a trial with 8,000 men testing Avodart versus placebo
are expected by 2009.
While clinical trials testing the effectiveness of cholesterol-lowering
statins or increased dietary fiber to reduce colon cancer
risk have yielded inconclusive results at best, prevention
strategies with aspirin, a non-steroidal anti-inflammatory
drug (NSAID), have yielded positive data. In two studies,
aspirin taken daily for three years was shown to reduce polyps,
a precursor to colorectal cancer, by 19 to 35 percent in people
at high risk for the disease.
Celebrex® (celecoxib), another NSAID, is approved for
reducing the risk of polyps in people with familial adenomatous
polyposis, a rare genetic disorder that predisposes carriers
to develop colon polyps. Because of the risk of serious side
effects, such as heart attack, stroke and bleeding from stomach
irritation, experts only recommend NSAID use for cancer prevention
for people at high risk of developing colorectal
Reprinted with permission from CURE: Cancer Updates, Research,
& Education. CURE provides the latest in cancer information
for patients and their caregivers free of charge. To sign
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