Hope for boys left infertile from cancer treatment as medical breakthrough means they could still have children of their own later in life

• Up to 30% of children who survive cancer will be infertile as adults
• In animal research, scientists froze testicular tissue before implanting it back
• The tissue created sperm, pregnancies, and even a live birth 
• But the method wouldn’t be appropriate for some cancer survivors

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Young boys with cancer whose treatment makes them infertile have hope from a scientific breakthrough.

Almost a third of men who survive childhood cancer will never become fathers because of the damage done to their bodies by powerful chemotherapy drugs and radiation.

But scientists have now discovered testicular tissue taken and frozen at a young age can produce a baby.

The method has worked successfully in monkeys – the closest animal to humans in scientific studies – paving the way for it to be tried in humans.

Pre-teenage boys cannot bank sperm to start a family after cancer treatment, because they are too young to produce it. At such a young age, many have to face the fact they will never become fathers in later life.

A medical breakthrough means boys who undergo fertility-destroying cancer treatment could still have children of their own later in life, after scientists at the University of Pittsburgh School of Medicine created a live birth in animal research

In 2015, it was reported that Nathan Crawford, a nine-year-old with an inoperable brain tumour, had become the first schoolboy in Britain to store his testicular tissue in the hope this might work instead.

The latest study suggests it might indeed, after tissue taken from the testes of primates was ‘reactivated’ to produce sperm.

This sperm was used to fertilise eggs, using a technique from IVF, and was able to produce a live monkey baby last year.

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Dr Kyle Orwig, senior author of the research, from the University of Pittsburgh School of Medicine, said: ‘This advance is an important step toward offering young cancer patients around the world a chance at having a family in the future.

‘These results from monkeys are really the last step on the road to being able to help children with cancer.

‘We hope to be doing trials of frozen testicular tissue on people within two to five years.’

An estimated 300 children are made infertile every year in Britain because of treatments for cancerous and non-cancerous tumours.

Women around the world have been able to give birth after becoming pregnant with frozen ovarian tissue, but the freezing of testicular tissue is more experimental.

Researchers took tissue from rhesus macaques, before they had chemotherapy, which damages cells in the body and often leads to infertility.

Just like tissue from young boys, it contained no sperm but just the stem cells which become sperm when puberty hits.

The tissue was frozen, thawed and transplanted back into the monkeys at an older age after puberty, just as it would be in cancer patients, so that brain hormones could trigger the testosterone needed to kick-start sperm production.

The study, published in the journal Science, reports that 100 per cent of these tissue grafts, implanted under the skin of monkeys’ backs and scrotums for eight to 12 months, contained sperm. For one piece of tissue, the scientists were able to retrieve 21 million individual sperm.

It was simple to then inject them into the eggs of female monkeys, just as is done in human IVF, and create an embryo.

The sperm, which fertilised eggs as efficiently as would happen normally, created 11 viable embryos which were put into female monkeys. The first monkey baby born from implanted testicular tissue arrived last April and was named ‘Grady’ – short for ‘graft-derived baby’.

Although babies have previously been born from testicular tissue in mice and pigs, a monkey birth from frozen tissue is the best hope yet that the technique could work in humans.

However it may be problematic for children with leukaemia and similar blood cancers, as well as those with testicular cancer, as traces of the cancer may linger in their tissue. Researchers also caution that their experiment was done only in monkeys that had been castrated.

Allan Pacey, professor of andrology at the University of Sheffield, said: ‘Although many men who were treated for cancer as boys are still fertile, and are able to have their children without medical assistance, there are many that are not and this can be a source of great sadness for them and their partners.

‘Currently, the only option available to men who were made infertile through cancer treatment at a young age, and who don’t have any stored sperm, is for them to either use donor sperm, or to adopt, or remain childless.

‘This study is a great step forward, but it is important to remember that before we could attempt to use it in humans, further research would be needed to show that it is safe and that it works in the same kind of way.’

HOW IS A BOY’S FERTILITY DAMAGED DURING CANCER?

Both radiation therapy and chemo can reduce sperm production and might also affect sexual development. 

Radiation therapy aimed at the testicles, abdomen or pelvis can affect the cells that make sperm. It might also damage the cells that make hormones if given at higher doses.

Sometimes the testicles may be shielded or moved out of the radiation field during treatment to try to prevent this.

Sex hormone levels in the body are also influenced by the pituitary gland, so radiation therapy to the head area can affect sexual development and sperm production as well.

High doses of certain chemo drugs are more likely to affect the cells that make sperm, but very high doses can also affect the cells that make hormones.

Treatments that affect sperm production can alter the patient’s ability to father children. 

For some, this may be only temporary, but for others it may be long lasting or even permanent. 

For boys who have gone through puberty, sperm banking (collecting and freezing sperm samples) may be an option that can allow them to father children later in life. 

The risks of effects on fertility are less in boys who are treated before puberty.

Source: American Cancer Society

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