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Fertility preservation
EGG, SPERM & EMBRYO PRESERVATION
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Egg, sperm and embryo freezing

People choose to preserve their fertility for many different reasons. Some people want to focus on their careers without the ever-present ‘biological clock’ ticking away, while others just haven’t found the right person. Sadly, many adults and children face cancer diagnoses that threaten their future fertility. In many cases, they can take measures to preserve their fertility and have biological children if and when they are ready. Read ahead to learn more about common fertility preservation methods, information about freezing eggs and sperm before cancer treatments, and preserving fertility in children who have cancer.

Egg freezing

Retrieving and freezing your eggs is the same process as the first few stages of IVF.

You inject hormones to stimulate your ovaries, which causes them to produce multiple eggs (normally, only one or rarely two or three are released each month).

You then undergo surgery under general anaesthetic, during which doctors retrieve these eggs via a thin needle. Lab technicians then cryopreserve the eggs at extremely low temperatures.

For those in the UK, there is currently a ten-year limit on elective egg storage in the UK, but this is under current debate to increase to 55 years. Eggs frozen to preserve fertility during cancer treatments are not subject to any time limits.

When you decide to start trying to get pregnant, lab technicians will thaw your eggs, and you can have them fertilised with your partner’s sperm or donor sperm. However, thawing frozen eggs has a lower live birth rate than thawing embryos, so you may wish to freeze embryos instead or in addition to unfertilised eggs.

Sperm freezing

Sperm freezing is the most successful method of preserving a man’s fertility so he can try and have a family at a later date. It’s also used to store sperm so it can be used in someone else’s treatment.

You’ll be asked to produce a fresh sample of sperm which is collected  in a sterile container at a clinic It will then be mixed with a cryoprotectant, a special fluid used to protect the sperm from damage during freezing. Technicians can then thaw the sperm when you are ready to undergo fertility treatments. It can be used for IUI (intrauterine insemination), a minimally invasive procedure that can be medicated or unmedicated.

If your future partner has fertility issues of their own, you can also use your thawed sperm for IVF treatments.

Embryo freezing

While thawing frozen sperm and eggs has a high success rate, the success rate is even higher with frozen embryos. For this reason, many couples choose to create embryos rather than freeze their sperm and eggs separately. Embryos have a 95% chance of surviving the thawing process.

To create an embryo for freezing, lab technicians combine an egg with several thousand sperm (IVF) or inject a single sperm directly into an egg (ICSI). They then observe the dish in a controlled setting. If an egg is fertilised and an embryo is created (which takes 5 or 6 days), it can then be frozen for future use. When the female partner is ready to have a baby, the embryo will be thawed, and doctors will implant it in her uterus. IVF and ICSI success rates vary from 5 – 30% per cycle, which often depends on the woman’s age when freezing her eggs.

As frozen embryos have a higher live birth rate than frozen eggs, some single women opt to freeze both their unfertilised eggs (in case they meet a future partner) and embryos created with donor sperm.

Fertility and Cancer Treatment

With a diagnosis of cancer, do consider fertility preservation ahead of treatment

Fertility Preservation Before Cancer Treatment

If you have received a cancer diagnosis and treatment is chemotherapy, this treatment can damage the ovaries, uterus, or testes, causing issues to conceive naturally. If you are diagnosed with cancer and want to protect your fertility and ability to have children in the future, it is important to think about fertility preservation before starting your treatment.

Many doctors and nurses will not ask you about fertility preservation – and you may often have to bring up your wishes and ensure that they are actioned. In the UK, the NHS will cover fertility preservation treatments for almost all cancer patients under the age of 40. In the US, the coverage will depend on your insurance. If your policy does not cover these treatments, you can approach charities to help you with the costs.

How do Cancer Treatments Damage Fertility

Chemotherapy and radiation treatments used to treat cancer (and occasionally lupus and other autoimmune diseases) can reduce the number of eggs your ovaries can produce. This can be a temporary effect, or it can cause early menopause and prevent you from conceiving children naturally. 

Some of the most common chemotherapy drugs to affect male and female fertility include:

  • Busulfan
  • Carboplatin
  • Carmustine
  • Chlorambucil
  • Cisplatin
  • Cyclophosphamide
  • Cytosine arabinoside
  • Doxorubicin
  • Ifosfamide
  • Lomustine
  • Melphalan
  • Mitomycin-C
  • Nitrogen mustard (mechlorethamine)
  • Procarbazine
  • Temozolomide
  • Thiotepa
  • Vinblastine
  • Vincristine

Remember – the higher the dose, the more likely the damage. Permanent damage to fertility is particularly likely when an individual is treated with both abdominal or pelvic radiation and chemotherapy. 

In contrast, these chemotherapy medicines are less likely to cause permanent infertility:

  • 5-fluorouracil (5-FU)
  • 6-mercaptopurine (6-MP)
  • Bleomycin
  • Cytarabine
  • Dactinomycin
  • Daunorubicin
  • Epirubicin
  • Etoposide (VP-16)
  • Fludarabine
  • Gemcitabine
  • Idarubicin
  • Methotrexate

In addition to treatment, some people may also need surgeries to remove their reproductive organs in order to stop the spread of cancer. They then lose their testicular function, uterus, ovaries, or fallopian tubes. In women, some cancer surgeries can cause damaging scarring, called adhesions, that block the fallopian tubes or ovaries and prevent pregnancy.

Freezing Eggs Before Cancer Treatments

As detailed above, stimulating, collecting, and freezing eggs is a complex process that involves time and invasive medical treatments. Depending on a woman’s personal medical circumstances, this process can take as little as two weeks and as long as three months. In some cases, cancer treatment can wait or be altered while a woman undergoes this process.

However, rapid treatment is necessary in the face of aggressive cancer, and there is no time to stimulate, collect, and freeze eggs.

Freezing Sperm Before Cancer Treatments

Freezing sperm is a great option if you or your partner are about to start treatments that could damage sperm. Your doctor can freeze your semen before your treatment starts, so it will be available later when you want to conceive a child. All sperm collection should be done before any treatments begin.

Freezing Embryos Before Cancer Treatments

The feasibility of freezing embryos depends on which partner has cancer. If it is the female partner and she is dealing with aggressive cancer, there is often no time to go through the egg retrieval process required to create embryos. However, if it is the male partner, even if he has aggressive cancer, his sperm can be frozen for a short time while his female partner goes through the stimulation and retrieval process. Then, embryos can be created and frozen for future use.

Your embryos can stay frozen until your doctor gives you the green light to use them, which is usually at least two years after a woman has finished chemotherapy treatments

Ovarian and Testicular Tissue Freezing Before Cancer Treatment

It is not always possible to collect eggs or sperm before cancer treatments need to begin. Thankfully, there is a newer fertility preservation option that has been successfully used to preserve ovarian and testicular function since 2001.

Ovarian Tissue Preservation

There is one main problem with female fertility preservation and cancer – time. If a woman discovers that she has cancer spreading throughout her body, she often doesn’t have time to go through the long and complex process of ovarian stimulation and egg retrieval.

If a child is diagnosed with cancer and her parents want to preserve her fertility, egg retrieval is not possible or appropriate.

In some of these cases, ovarian tissue preservation is an option. However, it too is an invasive surgery. Doctors remove an ovary or strips of ovarian tissue during a laparoscopy under general anaesthesia. This tissue is frozen until the patient is ready to try to get pregnant and then transferred back into her body. This surgical procedure is successful approximately 50% of the time.

Testicular Tissue Preservation

Even though sperm collection is a far quicker and less invasive procedure, in some cases, ejaculation is not possible, particularly in young children. In these cases, an experimental procedure called testicular tissue freezing may offer some hope.

Tissue rich in stem cells is collected from the testes with the hopes that scientists will be able to create sperm from the stem cells in the near future. This treatment could also be an option for men who produce no sperm in their semen (azoospermia). However, no live births have yet resulted from this technique.

Preserving Fertility in Children and Young Adults with Cancer

Childhood cancers now have high treatment success rates, with more than 80% of children and young adults cured. However, fertility is impacted in 10 to 15% of children and young adults with cancer. The mental, social, and cultural implications of infertility can be severe, and children who grow up knowing they cannot reproduce often experience anxiety and depression.

Thankfully, the University of Oxford and the NHS have teamed up to provide cryopreservation of children’s reproductive tissue before they go through certain cancer treatments. As a result, children, young adults (up to age 35), and even babies can qualify to have their reproductive tissues frozen until they are ready to have children of their own. These treatments are available for both male and female patients.

Fertility Preservation Before Gender Confirmation Treatments

Some trans and non-binary people take hormonal medications that can temporarily or permanently damage their fertility. Similarly, some undergo gender confirmation surgeries that involve removing the ovaries or testes. In these cases, some people choose to preserve their fertility before they start their gender confirmation treatments.

Other trans and non-binary people may experience severe gender dysphoria at the idea of producing sperm, taking hormones to produce eggs, or carrying a child, even if able. In these cases, some people choose to preserve their fertility when they transition so that they never have to worry about triggering dysphoria in the future.

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