A new fertility treatment may some day help women left infertile by cancer treatment to have children.

Researchers at the Center for Reproductive Medicine and Infertility at Cornell University in New York published a study of the new treatment in Tuesday's online issue of the journal The Lancet.

In the study, a 30-year-old American woman was successfully treated for breast cancer. Since chemotherapy can trigger early menopause, doctors had removed an ovary, cut it into sections and froze it in hopes of restoring her fertility.

Only one embryo survived.

Six years later, the woman wanted to have a child. Researchers thawed a section of her ovarian tissue, implanted it into her abdomen just beneath the skin and gave her fertility drugs.

A few months later, the tissue was producing thousands of immature eggs. Doctors were only able to retrieve 20, eight of which they tried to fertilize. Two of those eight formed embryos.

"One of those embryos didn't grow appropriately," said Dr. Tom Hannam, an infertility specialist in Toronto. "They did genetic testing and it was not healthy. But the other looked good, it actually looked ideal."

Dr. Tom Hannam

Although it looked ideal, the woman never became pregnant. Researchers say it is still a significant achievement.

"Without a pregnancy we can not claim total success, but I believe this is a move in the right direction," said lead researcher Dr. Kutluk Oktay of Cornell.

Ethical issues surround the procedure. If there are cancerous cells in the tissue when it's frozen, there's a risk of re-introducing the cancer in the patient, which happened in mouse experiments.

Dr. Kutluk Oktay.

Jeffrey Nisker, an obstetrics and gynecology professor at the University of Western Ontario, wonders about the issue of consent in the case of girls facing chemotherapy.

"Who should be making the decision: an eight-year-old child, should it be the parents, should it be both together?" Nisker asked.

Some doctors also worry healthy women will take advantage of the procedure to put off having children until after menopause, which Oktay said is a possibility.

"Our main purpose was to get a baby, but what happened simultaneously was that hormone production was resumed and in many ways, menopause was reversed," he said.

Doctors in Canada are interested in ovarian tissue transplants for cancer patients but they say it's too soon to tell women they can preserve their fertility simply by freezing their ovaries.