Child cancer patients' future fertility hopes on ice

Somewhere in a freezer at a Melbourne fertility clinic, sits something that belongs to six-year-old Stella Davis.

It was removed from her when she was a toddler, while she was undergoing intensive chemotherapy for a germ cell cancer that was refusing to go away.

The tissue sample, taken from one of Stella's ovaries, is of no use to her now. And it might not be for decades to come, if ever.

But it represents hope.

There is a risk that Stella may not be able to have children of her own in the future, because of the multiple rounds of chemotherapy she had to endure after the discovery of a large tumour on her tail bone.

In response, doctors at the Royal Children's Hospital in Melbourne offered her parents the option of preserving some of her ovarian tissue.

Stella's mother Lara MacEwen said making the decision to preserve her daughter's ovarian tissue was an easy one.

"I'm very realistic," she said.

"We know that there isn't a 100 per cent chance that it is going to work, but you have to be hopeful, and science and technology is progressing so fast.

"Who knows where we will be in 15 years or so?"

One might assume that any parent of a child in Stella's situation would do all they could to help their child.

But the issue is more fraught than it appears, success with tissue from young children is unproven and could rely on technology that does not yet exist.

The topic has been recently investigated by University of Melbourne bioethicist Rosalind McDougall and her colleagues, who found that for many children the removal of reproductive tissue was ethically permissible, but not ethically required - which meant the decision was up to parents.

"Even though the surgery to collect the tissue is quite straightforward, the techniques of using the tissue are still being developed," Dr McDougall said.

"[In cases where doctors believe] it is going to be medically safe for a child, it is appropriate to offer the procedure but because of the speculative nature of the future benefit we think it is justifiable for parents to go forward with the procedure - or decide not to."

Although 80 per cent of paediatric cancer patients now survive their illness, 16 per cent of girls will be left infertile and treatment can also deplete boy's sperm.

The Royal Children's Hospital has, since 2013, been routinely offering the fertility preservation procedure for appropriate patients, with tissue samples taken from 100 girls and 40 boys.

These cases were guided by an ethical framework, which asks clinicians to consider questions such as whether the child has already received treatment that may have damaged the tissue, whether the procedure could delay cancer treatment and if parents realised that the procedure would not guarantee future fertility.

The process sees ovarian or testicular tissue taken from young cancer patients and frozen in a process of "cryopreserving", in the hope that by the time the children are grown, medical technology will have advanced to allow the tissue to be used to create a baby.

In girls, it is thought the harvested tissue may be replanted when the patient is ready to have children.

Royal Children's Hospital paediatric oncologist Professor Michael Sullivan said it was also conceivable that eggs could one day be recovered from the frozen ovarian tissue.

Professor Sullivan said that globally there had been at least 100 births using cryopreserved ovarian tissue, but only one report of a live birth from tissue that was removed before the girl hit puberty.

"That's because tissue has only been stored for a relatively short time," he said.

The technology is less advanced when it comes to boys. It is estimated that births relying on testicular tissue for sperm "may be decades away".

This story Child cancer patients' future fertility hopes on ice first appeared on The Sydney Morning Herald.