|
Wed January 8, 2003 10:43 AM ET
By
Pat Hagan
LONDON
(Reuters Health) - Researchers say the breast cancer drug
tamoxifen
may help cancer patients retain their fertility after a woman
who
took it to stimulate egg production gave birth to twins.
According
to doctors at Cornell University in New York, this is the
first
recorded case of a successful pregnancy and birth arising from the
use
of tamoxifen as an in vitro fertilization (IVF) treatment.
In
a study looking at its effectiveness as a fertility drug, researchers
discovered
it boosted egg production in 12 women who had survived breast cancer.
Although
tamoxifen has been known to be an ovarian stimulant for the past
30 years, its use in IVF treatment has been neglected because of its
success as a breast cancer therapy, according to the report.
The
new findings, published in the journal Human Reproduction, suggest it
could play a key role in helping breast cancer patients who want to freeze
embryos because they risk ovarian failure due to the toxic effects
of chemotherapy.
"Sometimes
the best ideas are the obvious ones and tamoxifen seemed the obvious
choice of drug to test, although to my knowledge no one has tried
it before in breast cancer patients," lead researcher Professor
Kutluk
Oktay said in a statement.
"We
hypothesized that tamoxifen stimulation would result in higher numbers
of embryos compared with natural cycle IVF, while theoretically shielding
breast cancer cells against estrogen." Many doctors are reluctant
to use traditional methods to stimulate the ovaries of breast cancer
patients to produce more eggs, for fear that the drugs could trigger
cancer growth.
Tamoxifen
was originally developed back in the mid-1960s as a contraceptive
before finding favor in Europe as an ovarian stimulant.
But
after its anti-cancer properties were discovered in 1976, its use as a
fertility aid declined.
Oktay,
from the Center for Reproductive Medicine and Infertility at Cornell's
Weill Medical College, said the study arose from a desire to find
a safe way of preserving fertility among the 15% of breast cancer patients
who are still of reproductive age when diagnosed with the disease.
Even
if their fertility survives chemotherapy, many of these women can simply
run out of time to have a child because they are advised to wait up
to five years before trying to conceive.
"These
women can try natural cycle IVF without ovarian stimulation, but typically,
no more than a single embryo can be achieved for immediate use
or freezing," said Oktay. "So we need to find a safe way of increasing
the number of embryos."
Twelve
breast cancer patients were given 40 to 60 milligrams of tamoxifen
for seven days, starting two or three days into their menstrual
cycle, and monitored for egg production.
To
gauge the effects, researchers compared them with a group of five cancer
patients who had undergone natural cycle IVF.
The
results showed the women taking tamoxifen produced an average of 1.6 mature
eggs compared to 0.7 in the non-tamoxifen group, or control group.
All 12 then went on to generate embryos to freeze for later attempts
at pregnancy, compared to three out of the five controls. None of
the women has since suffered a recurrence of their cancer.
One
patient who had two embryos transferred has successfully given birth to
twins, the researchers announced.
Oktay
added: "We exploited tamoxifen's dual action as an ovarian stimulant
and an anti-cancer agent.
"It
would be especially fitting if a drug that has saved so many women's lives
should also turn out to be a means of preserving their fertility."
Dr.
Mark Johnson, a specialist in assisted conception at the Imperial College
of Science, Technology and Medicine in London, said tamoxifen's benefits
as an IVF treatment came as no big surprise. Other doctors in
the
UK, he said, have used the drug to stimulate the ovaries in women with
polycystic ovary syndrome but this was the first documented case of a
successful birth. Polycystic ovary syndrome is a condition marked by
infertility,
excess facial hair and obesity.
"I'm
sure they are right to say that but the numbers of women who will benefit
are quite small," Johnson said. "The numbers of people with breast
cancer who have fertility problems are not that great."
SOURCE:
Human Reproduction 2003;18:90-95.
|
[ 