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Cancer study drug results challenged (crossposted) - long
Posted on Tue, Jun. 06, 2006
Cancer study drug results challenged
NO DIFFERENCE IN BREAST CANCER MEDICATIONS
By Marilynn Marchione
ATLANTA - Final results from a big study comparing two drugs for
preventing breast cancer in high-risk women challenge the government's
claim that raloxifene is better than the old standby, tamoxifen.
At a news conference in April, the National Cancer Institute, which paid
for the $88 million study, said both drugs were equally effective at
lowering the risk of serious forms of breast cancer. But users of
raloxifene, the newer drug, had 36 percent fewer uterine cancers and 29
percent fewer blood clots, making it a safer choice, government
However, data made public Monday shows that the uterine cancer results
were not statistically significant. That means the actual number of cases
differed so little that they could have happened by chance.
Scientific standards have long held that such results only suggest trends
and are not definitive, certainly not to the extent that government
scientists portrayed them to be.
Furthermore, so few blood clots occurred in the study that some doctors do
not believe that result proves raloxifene is better.
Also, it is not known whether raloxifene's cancer-prevention benefit will
last years after women stop taking the pills, as tamoxifen's is known to
do. So far, raloxifene is approved only for preventing the bone disease,
``There is some genuine controversy here,'' said Dr. Len Lichtenfeld,
deputy chief medical officer of the American Cancer Society. Not everyone
agrees ``that there was a clear winner in this study,'' he said.
The news generated heated discussions at a meeting of the American Society
of Clinical Oncology, where the study's results were to have been reported
first, so experts could review them as they were released to the public.
Instead, the cancer institute hastily called the press conference and did
not disclose in materials sent to reporters that some key results were not
``It needs to be publicly vetted because it's not clear either way'' which
drug is better, said Dr. Roy Herbst, a University of Texas M.D. Anderson
Cancer Center doctor who helped run the oncology meeting, the world's
largest cancer conference.
Tamoxifen has been used for decades to treat and prevent breast cancer. It
blunts estrogen, which fuels the growth of most tumors that occur after
menopause, but also acts like estrogen elsewhere in the body and has
previously been shown to raise the risk of blood clots and uterine cancer.
Raloxifene, sold as Evista by Eli Lilly & Co. for osteoporosis, is
believed less likely to cause these problems.
The study tested the drugs in nearly 20,000 postmenopausal women at high
risk of breast cancer because of gene mutations, family history or other
reasons. (Raloxifene's safety in premenopausal women is unknown.)
Results were released Monday at the cancer meeting and will be in the June
21 issue of the Journal of the American Medical Association.
Raloxifene Equals Tamoxifen in Preventing Breast Cancer
06.05.06, 12:00 AM ET
MONDAY, June 5 (HealthDay News) -- The osteoporosis drug raloxifene is as
effective as the cancer drug tamoxifen in reducing the risk of invasive
breast cancer in postmenopausal women, new research shows.
But the two drugs vary in "side-effect profiles," meaning each may be
appropriate for a different set of women. This is somewhat at odds with
previous proclamations, which had labeled raloxifene a "clear winner" over
The latest results of the STAR (Study of Tamoxifen and Raloxifene) trial
were announced Monday at the annual meeting of the American Society of
Clinical Oncology, in Atlanta.
"Basically it's good news," said the study's lead author, Dr. D. Lawrence
Wickerham, associate chairman of the National Surgical Adjuvant Breast and
Bowel Project. "Postmenopausal women with an increased risk for breast
cancer have a new and effective option for chemoprevention of invasive
Dr. Robert Morgan, a medical oncologist with City of Hope Cancer Center in
Duarte, Calif., added, "This is important data. Both are very excellent
Although tamoxifen has been on the market for 30 years and has a proven
effect, many women and doctors have been hesitant to use the drug because
of side effects, such as hot flashes, vaginal dryness, decreased sex drive
Raloxifene is already used by 500,000 women for osteoporosis prevention
and treatment. Although it is not yet approved to prevent breast cancer,
experts hope gynecologists and primary-care physicians, who have
experience with raloxifene, will start prescribing it for breast-cancer
"We would expect that the STAR results would increase the numbers taking
the drug and decrease breast cancer occurring in the U.S. and around the
world," Wickerham said. "The STAR results are an important next step in
the elimination of breast cancer."
"It's obviously an important study. Not only does it add to our knowledge
but it provides another option for women at high risk of getting breast
cancer to consider," added Dr. Len Lichtenfeld, deputy chief medical
officer of the American Cancer Society. "If it gets more women into a
prevention strategy, then that's good news. It's important that both women
and their physicians recognize that a preventive strategy is available,
and it's important for women and their physicians to have conversations
with each other to determine which approach is best for them."
The STAR trial enrolled almost 20,000 postmenopausal women with an
increased risk for breast cancer. Participants were randomly selected to
take either 20 milligrams of tamoxifen or 60 milligrams of raloxifene
daily for five years.
Both drugs reduced the risk of breast cancer by about 50 percent, to about
four per 1,000 women a year, from eight per 1,000 women per year.
However, raloxifene was not as effective in preventing non-invasive breast
cancers as tamoxifen. "This is biologically intriguing, but we haven't
been able to define this," Wickerham said.
Women on tamoxifen had more uterine cancers, blood clots and cataracts.
There were no significant differences with regard to the incidence of
other cancers, heart problems, stroke, bone fracture or death, the study
The STAR findings were also released online Monday in the Journal of the
American Medical Association, and will appear in the journal's June 21
Another report released Monday at the ASCO meeting that was culled from
STAR data found that quality of life, based on both mental and physical
indicators, was about the same between women in the raloxifene group and
those in the tamoxifen group.
There was slightly greater decline in sexual function among women in the
tamoxifen group, particularly younger women.
"It was a very subtle, statistically significant difference, but whether
it is clinically significant and meaningful is hard to say," said Dr.
Patricia A. Ganz, the study's lead author and director of the Division of
Cancer Prevention and Control at the University of California, Los
Angeles' Jonsson Comprehensive Cancer Center.
Tamoxifen seemed to do better in the areas of musculoskeletal pain, weight
gain and painful intercourse, while raloxifene came out ahead in vasomotor
symptoms, leg cramps and gynecological symptoms, the study found.
"We now have two equally effective drugs to be used in preventing breast
cancer," Ganz said. "We can start woman on one drug and if, after three
months, she's having a symptom that she feels is not tolerable, we can
switch to the other drug. But we want women to be able to take a drug to
prevent or reduce incidence of breast cancer. It does us no good if she
doesn't take the medication."
For more on the STAR trial, visit the U.S. National Cancer Institute.
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