MONDAY, March 8, 2004 (HealthDayNews) -- For the first time, scientists have been able to obtain a human egg from frozen ovarian tissue, fertilize it, and get an embryo.
Although the novel procedure did not result in a pregnancy, it does offer hope for the hundreds of thousands of women who go through early menopause as a result of cancer treatment.
"The most significant achievement in this study is to show that ovarian tissue can be frozen and banked for as many as six years and can still retain its function, such as producing estrogen hormone and eggs that are able to be fertilized and undergo development into embryos," says Dr. Kutluk Oktay, lead author of the study. "The findings give further hope that this procedure eventually can result in a pregnancy."
The study appears in the March 13 issue of The Lancet, which released the results online Monday.
Other experts warn that the results, while exciting, are still highly experimental.
"It is too early to offer this service as a routine clinical option," Dr. Robert Rebar, executive director of the American Society for Reproductive Medicine, cautioned in a statement. "Patients should only be offered cryopreservation of eggs or ovarian tissue as part of an approved research trial."
Cancer treatments such as chemotherapy, radiation, and surgery often induce premature menopause and infertility in women who would otherwise be of reproductive age. Options for having a baby are currently limited, and include going through in vitro fertilization before the cancer treatment, then freezing the embryos. However, this takes time that many cancer patients just don't have. Women could also opt to freeze eggs before undergoing chemo or other treatments, another route that takes precious time. Also, the pregnancy rates using these eggs are low.
The current paper describes a technique that has previously been successful in animals. Ovarian tissue was removed from a 30-year-old woman about to undergo chemotherapy for breast cancer, then frozen and stored.
Six years later, the tissue was transplanted beneath the skin of the abdomen, near the bikini line (the tissue was first examined to make sure it didn't contain any residual cancer).
"It's above the muscle. If you stick a needle right underneath that space, you can feel these eggs," says Oktay, an associate professor of reproductive medicine and obstetrics and gynecology at the Center for Reproductive Medicine and Infertility at New York Presbyterian/Weill Cornell in New York City.
In fact, that is exactly what happened: 85 days after the tissue transplantation, the woman noticed a pea-size lump. Over the next eight months, 20 eggs were retrieved, of which eight were suitable for in vitro fertilization (IVF). One was fertilized with the husband's sperm, developed into a four-cell embryo, and was transplanted into the woman's uterus.
The initial transplantation took place under local anesthesia while the egg collections were done using a spray anesthetic.
That this woman did not become pregnant is not necessarily an indication of how viable this procedure is. "One embryo transfer is not a test for success in any procedure," Oktay says. "This was really our first attempt at that, and we will be attempting more in the same woman."
No one knows if multiple transfers will be enough to determine success. "It's impossible to answer at this stage whether this is going to be an odds game, but pregnancies have already been possible in animal studies," Oktay says. "That gives us encouragement. There's a lot out there in terms of animal studies that tells us that there is a reasonable possibility of success."
In an accompanying commentary, Dr. Johan Smitz of the Center for Reproductive Medicine at the University Hospital of Vrije University in Brussels, Belgium, warns that it is always possible that ovarian tissue might contain cancer cells despite doctors' best efforts to hunt them down. Smitz also points out that no one can yet know if the preparation and freezing techniques will affect the health of the fetus.
Even though the procedure is not proven, many women are already opting to store ovarian tissue in the hope that it can be transplanted later.
Oktay says that, at his center, 50 or so women and girls have elected to have their ovarian tissue cryopreserved. "Once ovarian tissue is frozen, the patient has the luxury to wait for developments in technology," he says.
For more on infertility, visit the American Society for Reproductive Medicine or the InterNational Council on Infertility Information Dissemination.