Freezing Ovaries May Preserve Fertility

For women who undergo cancer treatment, loss of fertility is often a major concern. But a new experimental research program that will remove and freeze women's ovaries for possible future use could provide new hope, according to researchers.

Female cancer patients receiving treatment can lose their fertility because "you're trying many aggressive ways of killing cells," says program leader Teresa Woodruff of Northwestern University. Radiation and chemotherapeutic treatments can kill ovarian cells in addition to cancer cells.

The ovaries are made up of groupings of cells called follicles that each contain a single egg. After puberty, these follicles are periodically selected to mature and eventually ovulate.

Currently, emergency in vitro fertilization can be performed for some women with cancer: The woman is given hormones to induce more than one follicle to provide eggs that can later be fertilized outside the woman's body. But for women whose cancer is at an advanced stage, emergency IVF isn't an option.

Emergency IVF is also impossible to use for young girls with cancer. Woodruff says that for adult survivors of childhood cancer, "fertility is just their number one concern," but no viable option to help them has existed before.

Woodruff's technique would involve removing one of a woman's ovaries and cryopreserving, or freezing it. Later, the frozen immature follicles would be extracted and matured in the lab so that they could be fertilized.

Few ovaries have been cryopreserved, Woodruff said, and she only knows of one case in which a pregnancy resulted from the previous frozen tissue when it was re-implanted in the woman it was originally removed from.

Also, the researchers have so far only extracted and matured follicles from mice, but the technique has resulted in pregnancies in the mice.

Woodruff's program plans to enroll girls between the ages of 4 and 17 and women between the ages of 18 and 41 who cannot undergo emergency IVF. They will have one ovary removed, and 80 percent of it will be frozen for possible future fertilization while the remaining 20 percent will be used by researchers to test ways to extract and develop the immature eggs.

Woodruff said the technique could eventually be used in place of normal in vitro fertilization.

And because women lose follicles as they age, the procedure could also be used for young women entering a career requiring long years in school who haven't decided whether they want to have children, but want to preserve immature eggs "before their biological clock ticks off.

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