Scientists in Israel have successfully extracted and frozen eggs from the ovarian tissue of five year old girls with cancer in a hope of securing their fertility in later life.
The scientists, from the Department of Obstetrics and Gynaecology, Hadassah University Hospital, Jerusalem, were led by Dr Ariel Revel, who is talking about their research today at the 23rd Annual Conference of the European Society for Human Reproduction and Embryology (ESHRE), in Lyon, France.
The survival rate of childhood cancer is improving all the time, cure rates are now 70 to 90 per cent, and this prompts the question of how to preserve fertility in later adult life.
Aggressive cheomotherapy means that many children who survive cancer treatment are likely to be sterile in adulthood. The British Fertility Society puts this number at around 15 per cent of childhood cancer survivors.
Retrieving eggs from adult women involves stimulating the ovaries to produce eggs which are then removed, fertilized and frozen.
Although it is possible to remove and freeze the ovarian cortex, the tissue that contains the egg-producing follicles, the freezing invariably destroys the tissue. So this method would not necessarily help younger women to preserve fertility for later life.
The more successful way is to retrieve individual eggs from the folllicles, because these are more resistant to extreme cold.
Dr Revel and colleagues were astonished to find that it was possible to do this in girls as young as 5 to 10 years old, well before puberty.
“We were able to extract oocytes [cells that later produce eggs] using needle aspiration from very young girls,” said Dr Revel.
“For example, we found 7 eggs in a girl of 5 years old with Wilm’s tumour, 8 in an 8 year old with Ewing’s sarcoma, and 17 in a ten year old, also with Ewing’s sarcoma. We were then able to mature the eggs in vitro and freeze them for use in the future,” he explained.
Although girls as young as 5 participated, the median age of the girls in the research study was 16. A total of 167 eggs was found in all but one participant. The average find per patients was 8.5 eggs.
The researchers were able successfully to mature 41 of 130 eggs in vitro and they were then frozen.
As yet they don’t know if the study is successful because none of the eggs has been thawed; it’s early days, the patients are still young. They don’t know if any pregnancies will result, said Dr Revel and his team.
“But we are encouraged by our results so far, particularly the young ages of the patients from which we have been able to collect eggs. We believe that no younger patients have ever undergone egg collection, in vitro maturation, and egg freezing,” said Dr Revel.
“We are hopeful that the mature eggs can offer these girls a realistic possibility of preserving their fertility,” he concluded.
At the moment, such studies are in experimental stage, no services as yet exist that offer girls the possibility of preserving their ovarian tissue for use in what could be some 30 years later.
There are a number of issues that need to be addressed before what is currently experimental becomes clinical routine, as it is in the preservation of post-puberty sperm preservation for boys, says a British Fertility Society report. A lot of research is needed to establish the correct procedures and risk-benefit profiles.
Input will be needed from a wide range of disciplines, including psychology, paediatrics, oncology and reproductive medicine.
“The most efficient way of optimising all regimes for outcome of the cancer treatment and subsequent conception is by longitudinal and prospective data collection and review of the retained records of the various treatment details and these also need to be accessible for long term follow up,” says the report.
The girls who are likely to be offered such a service in a clinically routine sense are still to be born, it seems.
Click here for European Society for Human Reproduction and Embryology (ESHRE).
Click here for British Fertility Society.
Written by: Catharine Paddock
Writer: Medical News Today