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A new study suggests that women whose breast biopsy shows pre-cancerous cells may benefit from the drug
tamoxifen (brand name Nolvadex) to prevent breast cancer. The study also recommends that
all women over 60 or women with other factors that place them at high risk for breast
cancer maybe candidates for tamoxifen therapy.
In late 1998, tamoxifen became the
first drug to be approved for preventing breast cancer, after research showed it reduced
the chance of developing breast cancer by 50% in women with at high risk. The October 29,
1998 press release announcing the FDA approval of tamoxifen can be found online at www.nolvadex.com/pr2.cfm.
However, doctors have not been sure how to best determine how high a woman's breast cancer
risk needed to be before they recommended the drug, since tamoxifen carries its own risks.
This study and guidelines from the National Cancer Institute (NCI) can assist doctors in
determining which women should be offered tamoxifen.
The new tamoxifen recommendations were
issued by the American Society of Clinical Oncology (www.ASCO.org) at its annual meeting in Atlanta. The study suggests
that millions of healthy women could benefit from tamoxifen. The new research further
suggests that the drug may also benefit women who have abnormal cells that may or may not
develop into cancer. These abnormalities are lobular carcinoma in-situ (LCIS) or atypical
hyperplasia (AH). LCIS and AH have long been considered a signal that a woman may develop
breast cancer, said Dr. Donald Wickerham of Boston Medical Center. "But other than to
schedule regular mammograms and watch closely for cancerous changes, we were unsure what
to do."
The study analyzed 13,388 breast cancer
patients given either tamoxifen or placebo (an inactive substance given as if it were a
real drug). In the subset of more than 2,000 women with LCIS or AH, those who took
tamoxifen were 66% to 86% less likely to develop breast cancer within five
years, compared with those who took the placebo. Typically, women with either condition
are at a six percent increased risk of developing breast cancer within five years, he
said.
The ASCO recommendations provide
further guidance for women at high risk due to factors other than suspicious cellular
changes (shown on biopsy). Based on an analysis of existing scientific literature, the
ASCO guidelines say that women aged 35 or older with at least a 1.66% risk of getting
breast cancer over the next five years should be offered tamoxifen (see below for
summarized conclusions to the report). Age itself places a woman at risk, with almost 20
million women over 60 falling into this category.
How do
women determine if they are at risk for breast cancer?
An array of factors, from family
history and race to age at first menstruation and number of children are used to determine
if a woman is at high risk of breast cancer and merits the recommendation of tamoxifen.
Answers to the following questions can help a woman and her doctor determine her risk:
- Did you have your first period before
age 12?
- Did you have your first child after age
30?
- Are you childless?
- Did/does your mother have breast cancer?
- Do you have any sisters who have had or
have breast cancer?
- Do you have any daughters who have had
or have breast cancer?
- Have you ever had a breast biopsy?
- Did the doctor ever tell you that one of
your biopsies showed a premalignant or precancerous condition?
- Did the doctor ever tell you that one of
your biopsies showed early cancer that has not spread yet?
The National Cancer Institute (NCI) has
developed a software program called the Breast Cancer Gail Model Risk Assessment Tool to
help women and their doctors calculate their risk of breast cancer. The formal Breast
Cancer Gail Model Risk Assessment Tool incorporates statistical methods that were utilized
by the National Surgical Adjuvant Breast and Bowel Project to
screen patients for the groundbreaking Breast Cancer Prevention Trial. This tool is
available as a slide rule or computer software package but is intended for physician use
only. However, a version of this software has been prepared for public use and is
available online at www.nolvadex.com/prescreen.cfm
Click here to
learn more about breast cancer risks
ASCO
recommendations are disputed by some
Not everyone agreed with the ASCO's
study and recommendation, pointing out that tamoxifen carries its own risks. Tamoxifen
increases the chance of developing cancer of the uterine lining, potentially fatal blood
clots in the legs and cataracts. "We are not saying that all of these women should
take it, just that it should be offered," countered panel moderator Dr. Lori
Goldstein of the Fox Chase Cancer Center in Philadelphia. "What we are saying is that
these patients should be closely monitored, with regular breast exams and a discussion of
tamoxifen's risks and benefits."
The role
of raloxifene in preventing breast cancer
Recent research has suggested that a
drug known as raloxifene (brand name Evista) used to treat osteoporosis,
may offer a safer alternative to tamoxifen. Raloxifene is a related drug to tamoxifen.
However, ASCO said that there is not enough evidence to support a recommendation for use
of raloxifene in breast cancer prevention (more details can be found in the full ASCO
report).
A study of data on more than 7,500
women who took raloxifene or placebo to treat osteoporosis showed that the risk of breast
cancer was two-thirds lower in those who received raloxifene. But the study only followed
women for 40 months (3.3 years). A longer-term follow-up is need before a recommendation
can be made. Click here for information about the new STAR trial to
study and compare the effects of raloxifene and tamoxifen on the prevention of breast
cancer.
Summary
conclusion from the ASCO Report
"American Society of Clinical
Oncology Technology Assessment on Breast Cancer Risk Reduction Strategies: Tamoxifen and
Raloxifene"
"Conclusions: For women with a
defined 5-year projected risk of breast cancer of 1.66%, tamoxifen (at 20 mg/d for up to 5
years) may be offered to reduce their risk. [At a 1.66% risk, the benefits of tamoxifen
begin to outweigh the potential risks]. It is premature to recommend raloxifene use
to lower the risk of developing breast cancer outside of a clinical trial setting. On the
basis of available information, use of raloxifene should currently be reserved for its
approved indication to prevent bone loss in postmenopausal women. Conclusions are based on
single-agent use of the drugs. At the present time, the effect of using tamoxifen or
raloxifene with other medications (such as hormone replacement therapy), or using
tamoxifen and raloxifene in combination or sequentially, has not been studied adequately.
The continuing use of placebo-controlled trials in other risk-reduction trials highlights
the current unanswered issues concerning the use of such interventions, especially when
the influence on net health benefit remains to be determined. Breast cancer risk reduction
is a rapidly evolving area. This technology assessment represents an ongoing process with
existing plans to monitor and review data and to update recommendations in a timely
matter."
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