Image caption Chemotherapy can cause fertility problems

A discovery about how cells die could lead to ways to protect fertility in women having cancer treatment, researchers suggest.

Australian scientists found two specific proteins caused the death of early egg cells in the ovaries.

Blocking them meant cells survived the effects of radiotherapy, according to the study published in the journal Molecular Cell.

A UK expert said the research was an "encouraging starting point".

'Better protection'

The researchers from the Walter and Eliza Hall Institute, Monash University and Prince Henry's Institute of Medical Research looked at egg cells called primordial follicle oocytes, which provide each woman's lifetime supply of eggs.

They found that, when the DNA of cells is damaged through chemotherapy or radiotherapy, two proteins called Puma and Noxa cause the eggs to die.

This causes many female cancer patients to become infertile.

Increasing the understanding of the damage done and the potential for directly protecting the ovary and its contained oocytes has to be welcomed Dr Jane Stewart,, British Fertility Society

Low numbers of egg cells can also lead to a woman going through an early menopause.

When these cells were manipulated so they did not have the Puma protein, they did not die after being exposed to radiation therapy.

Prof Jeff Kerr, from Monash University, who worked on the study said: "This might ordinarily be cause for concern because you want damaged egg cells to die so as not to produce abnormal offspring."

But he added: "To our great surprise we found that not only did the cells survive being irradiated, they were able to repair the DNA damage they had sustained and could be ovulated and fertilised, producing healthy offspring.

"When the cells were also missing the Noxa protein, there was even better protection against radiation."

'Slow egg loss'

Prof Clare Scott, from the Walter and Eliza Hall Institute of Medical Research, who also worked on the lab and animal research, added: "It means that in the future, medications that block the function of Puma could be used to stop the death of egg cells in patients undergoing chemotherapy or radiotherapy.

"Our results suggest that this could maintain the fertility of these patients."

The researchers said that the discovery could also mean it would be possible to slow the loss of egg cells from the ovaries, thereby delaying early menopause.

Dr Jane Stewart of the Newcastle Fertility Centre at Life (the Life Science Centre), and a spokeswoman for the British Fertility Society, said: "Potential loss of fertility is an issue which worries many young women undergoing cancer treatment.

"Whilst it is not always an issue it can be unpredictable and the possibilities for effective fertility preservation in women remain limited.

"Increasing the understanding of the damage done and the potential for directly protecting the ovary and its contained oocytes has to be welcomed and - whilst this work may some way from being translated into clinical practice - it is encouraging as a possible starting point."