Girls as young as 5 who suffer from cancer can have eggs removed and frozen to preserve their fertility after chemotherapy, scientists have discovered.

A medical team in Israel has obtained immature eggs from the ovaries of young girls and ripened them in the laboratory, before freezing and storing them to give the patients a chance of starting a family when they grow up.

The achievement paves the way for thousands of prepubescent girls with cancer to achieve fertility after treatment that would normally leave them sterile.

While eggs, ovarian tissue and fertilised embryos can be harvested from female patients who are sexually mature, there have been few options available to children. Though girls are born with egg follicles, these become mature and fertile only after puberty.

Ariel Revel, a lecturer in obstetrics and gynaecology at Hadassah University hospital, Jerusalem, said that his group had been able to find immature eggs in the follicles of several girls aged between 5 and 10, and culture them into a potentially fertile state in a test tube.

“We were able to extract oocytes \ using needle aspiration from very young girls,” he told the European Society of Human Fertilisation and Embryology conference in Lyon.

“We found seven eggs in a girl of 5 years old with Wilms’ tumour, eight in an eight-year-old with Ewing’s sarcoma, and 17 in a ten-year-old, also with Ewing’s sarcoma.”

The same technique could also be employed on older women with cancer, some of whom cannot be given hormonal drugs to stimulate the ovaries before egg collection.

The scientists have yet to establish whether the eggs matured in the laboratory and frozen are viable, but tests suggest they should be capable of being fertilised. Gillian Lockwood, head of Midland Fertility Services, the only clinic in Britain to have live births from frozen eggs, said: “If it works it’s good news, because the big block has always been that we thought you had to wait until they reached puberty before getting the eggs. But this raises significant ethical issues. The parents will be making the decision in these cases, and it may be that they are keen to have grandchildren, and I don’t know if a very young girl will fully appreciate all of the arguments.”

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