Thanks for the heads up:
Health: Raloxifene shows dramatic results without the serious side effects of
tamoxifen, researchers say.
By THOMAS H. MAUGH II, Times Medical Writer
drug used to prevent osteoporosis in older women reduces
the risk of breast cancer by as much as 70% without any
serious side effects, researchers said Monday at a meeting of the
American Society for Clinical Oncology in Los Angeles.
The risk reduction produced by the drug, called raloxifene, is
about the same as that reported earlier this year for tamoxifen, but
the latter drug can increase the risk of endometrial cancer and blood
clots.
"This is a fantastic time for [breast] cancer prevention," said Dr.
Joseph Boyle of the European Institute for Oncology in Italy. "We
are very clearly on the path to the future."
"Coming on the heels of the recent tamoxifen study, this is very
exciting news," said Dr. Derek Raghavan of USC's Norris
Comprehensive Cancer Center. "However, these drugs are not for
every woman. Before advocating their widespread use, further trials
must be conducted to determine if these drugs actually prevent
breast cancer, or merely delay it."
Physicians also cautioned that women who are already taking
tamoxifen should not rush to switch to raloxifene because the two
drugs were tested in quite different groups.
Tamoxifen was studied in women who are at higher than normal
risk of developing breast cancer, and the study included women as
young as 35. Raloxifene was studied in post-menopausal women
who had a lower than normal risk.
"We just don't know what the rate of risk reduction [with
raloxifene] is going to be in the high-risk group," said Dr. Norman
Wolmark, chairman of the National Surgical Adjuvant Breast and
Bowel Project.
To find that out, the National Cancer Institute has already
scheduled a head-to-head trial of the two drugs that is expected to
begin toward the end of the year. "We certainly hope that raloxifene
will live up to the promising preliminary data," Wolmark said.
In 1998, 215,700 new cases of breast cancer will be diagnosed
and 43,500 women will die of the disease. It is the second leading
cause of cancer deaths in women after lung cancer, and the leading
cause of death among women between 40 and 55.
The current round of excitement was triggered April 6 when the
National Cancer Institute reported that tamoxifen, a drug used for
25 years to treat breast cancer, was the first agent found to prevent
the disease. Marketed by Zeneca Pharmaceuticals as Nolvadex, the
drug was shown to reduce the risk of breast cancer by 45% among
women who were at high risk because of a family history of the
disease.
That data was officially presented at the American Society for
Clinical Oncology meeting.
Unfortunately, the drug also increased the risk of endometrial
cancer and blood clots, which are normally rare. But experts noted
that endometrial cancer has almost a 100% cure rate. The five-year
survival rate for breast cancer ranges from 96.8% if the tumor is
detected before it has spread to only 20.6% if it is not detected until
it has spread to other parts of the body.
Because the mortality rate for breast cancer is so much higher
than that for endometrial cancer, "the benefits [of tamoxifen]
outweigh the risks relative to prevention, but women must be
advised of the risks and benefits prior to making a decision,"
Wolmark said.
Raloxifene is one of the first of the so-called designer estrogens,
synthetic chemicals that researchers hope will have the benefits of
estrogen without some of the risks.
The results with raloxifene, marketed as Evista by Eli Lilly &
Co., came from a study designed to test its efficacy in reducing
fractures caused by osteoporosis in older women. The study, led by
Dr. Steven R. Cummings of UC San Francisco, studied 7,704
healthy women with low bone density and no family history of
breast cancer.
Curiously, women with osteoporosis have only about one-third
the normal risk of developing breast cancer, he noted. While this
would put the study group at lower risk than the general population,
the researchers believe the results of the study are valid because all
the women in it had osteoporosis.
Two-thirds of the women in the study received raloxifene and
the remainder got a placebo. Over a period of 29 months, there
were 21 cases of breast cancer in the placebo group, compared to
11 cases in the treated group--which was twice as large. That
translates to a 70% reduction in cases, somewhat larger than that
observed with tamoxifen.
"That's a very strong effect," Cummings said.
There were only four cases of endometrial cancer in each group,
he added, too small a number to determine if the drug might be
exerting a protective effect there also. The risk for blood clots was
the same in the two groups.
The researchers will continue the study for another four to five
years to see how long the benefits persist, Cummings added.
Because the drug is already being marketed for use in preventing
osteoporosis, physicians are free to prescribe it for any purpose
they feel appropriate--including cancer prevention. But some
experts, such as Dr. Michelle Curtis of the University of Texas's
Lyndon Johnson Hospital, warned against such use.
"This is exciting," she said, "but all it really means is that we need
to design trials looking specifically at breast cancer and raloxifene.
We can't extrapolate results from a study that wasn't designed to
look at that."
Cummings countered that the results were so dramatic that they
were extremely convincing, even if prevention of breast cancer was
not the primary purpose of the study.
Curtis also urged that post-menopausal women who are already
taking estrogen replacement therapy not abandon it in favor of
raloxifene. Estrogen, she noted, has been found to provide a strong
reduction in the risk of heart disease, while raloxifene has not. "And
heart disease kills 10 times as many women as breast cancer," she
said.
* LIFE-SAVING TEST: A study says Prostate-Specific
Antigen (PSA) test should cut such cancer deaths by 69% |
