Paris (AFP)

A 34-year-old French woman who could not get pregnant after treatment for breast cancer was able to give birth to a child thanks to a new technique consisting in collecting her immature eggs before freezing them.

"This success represents an important advance in the field of fertility preservation," rejoiced Michaël Grynberg, director of the department of reproductive medicine at Antoine Béclère de Clamart hospital (Hauts-de-Seine), where this "world first" took place in the context of cancer.

Women under the age of 40 who are going to undergo treatment that may affect their fertility, such as chemotherapy, are offered to freeze their oocytes to preserve their chances of future pregnancy.

Normally, eggs that have reached maturity are taken after hormonal stimulation, but in hormone-dependent breast cancer, as was the case with Professor Grynberg's patient, stimulation is contraindicated.

His team therefore took seven immature oocytes before maturing them in the laboratory for 48 hours, then vitrifying them (an ultra-rapid freezing method which allows better conservation), details an article published Wednesday in the journal Annals of Oncology.

The patient was then treated for her breast cancer with chemotherapy.

After five years without relapse, she was declared cured but could not conceive, due to the treatments received. Her oocytes were then thawed and inseminated in vitro. One of the five eggs thus formed was successfully implanted, and the patient gave birth in July 2019 to a healthy baby boy named Jules.

This in vitro maturation technique (IVM) had already made it possible to give birth to children after immediate fertilization and implantation, without freezing.

The same team, in collaboration with the Jean-Verdier hospital, also announced that it had used it in June 2019, in association with embryonic vitrification, to allow a young woman with early menopause to give birth to twins.

But "so far, there has been no successful pregnancy in patients treated for cancer from eggs that have been subjected to both IVM and vitrification," says Annals of Oncology in a press release.

"We show that this technique, even if it is undoubtedly a little less effective today" than the freezing of oocytes taken at maturity, "can still allow to have children", underlined Michaël Grynberg with l AFP.

Two other pregnancies are currently in progress at the Clamart University Hospital after using the same technique, he added.

In breast cancer, around 40% of 40-year-old women become infertile because of their treatment, and 15% to 20% of 30-year-old women, estimates the obstetrician-gynecologist, stressing the importance of preserving fertility. in young women being treated for cancer.

© 2020 AFP