Freezing - introduction

Freezing

There are three freezing options which may help preserve a woman’s fertility:

Eggs, embryos and ovarian tissues can be frozen and stored for many years. When the time is right, they can then be thawed and used for a pregnancy after cancer treatment has been completed.

Different methods of freezing are available to preserve eggs, embryos and ovarian tissue. Cryopreservation is a method of ‘slow freezing’. Vitrification is a newer method of ‘fast or flash freezing’. This method has been shown to improve the chance of eggs and embryos surviving the thawing process and make the pregnancy success rate higher.

Some women, if they have a male partner, may be able to freeze both eggs and embryos. They may have more fertility options available to them in the future after their cancer treatment.

Ovarian tissue freezing is a new method of fertility preservation. This could be another option for women with no male partner.

Embryo Freezing

This option means that matured eggs are taken from a woman’s ovary and fertilised with sperm through in-vitro fertilisation (IVF). This is done in a laboratory. The fertilised eggs (embryos) are then frozen and stored for future use. When a woman is ready to become pregnant the stored embryos are put back into the womb.

Who is it for?

Women who have gone through puberty, and:

  • Have time to go through a cycle of fertility treatment before starting cancer treatment.
  • Have a male partner, as it requires both eggs and sperm for the egg to be fertilised.

What does it involve?

You will need to have hormone injections to stimulate the ovaries (ovarian stimulation) for about 2 weeks. Eggs are then collected through a fine needle passed through the wall of your vagina up to the ovaries. This is done under sedation. You may be able to go home a few hours later.

If you are in a relationship and create and store an embryo with your male partner you will need the consent of your partner before the embryos can be used. This is important, because if you later split up, he may not want you to use the stored embryos.

 If you do not have a male partner, the use of donor sperm is an option. In this case, you do not need the consent of the donor to use the embryo in the future.

Frozen embryos can be stored for 10 years. This can be raised by 10 year periods (up to 55 years in total) in some situations.

What is the chance of having a baby after embryo freezing?

It is difficult to be certain how likely it is that embryo freezing will result in a live birth. The number of cancer patients who have used frozen embryos is small. Most of the data comes from women without cancer who have used a frozen embryo to have a baby.

This data shows the chance that embryo freezing will help a woman to have a baby after cancer treatment is around 30 in 100 (around 30%).

The chance of having a baby after embryo freezing depends on a number of factors. These are:

  • Your age at the time the eggs are collected. Women who are younger than 35 years of age have a higher chance. This is around 40 in 100 (40%). Women over 35 years old will have a lower chance. This is around 20 in 100 (20%).
  • The number of eggs collected.
  • The number and quality of embryos frozen.
  • The health of your partner’s sperm.
  • The fertility clinic where embryo freezing has been carried out.

For more information on national average success rates and the number of successful live births for each licensed fertility clinic visit the HFEA website www.hfea.gov.uk.

Will this option affect the health of the baby?

No, the data suggests that the health of a baby born using frozen embryos will not be affected.

Are there any side effects of the fertility treatment used in embryo freezing?

The fertility drugs used to stimulate egg production can cause side effects such as headaches, mood changes, hot flushes, and irritation of the skin. The fertility drugs may also cause the ovaries to over respond and this can lead to a condition called OHSS. Once you start your treatment it is advised that you ask your fertility care team about the symptoms of this condition and how to contact them if you need to.

When the ovaries are stimulated to produce lots of eggs, the levels of the hormone oestrogen go up. This could be a concern in women who have an oestrogen sensitive breast cancer. These women can be given a drug called Letrozole (Femara). This lowers the levels of oestrogen in the blood stream.

In an attempt to obtain egg cells there is a chance of bleeding, infection and puncture to the bowel, but this is rare.

There may be a concern for women with pelvic cancers, where there could be a spill of cancer cells from the ovary into the abdomen following egg collection.

If more than one embryo is replaced, there is a chance of multiple births (twins, triplets). All pregnancies have a risk of miscarriage, and ectopic pregnancy (a pregnancy outside of the womb).

IVF can be physically and emotionally draining, and pregnancy may not occur.

Will this option delay the start of my cancer treatment?

It takes around two weeks from the time of starting ovarian stimulation until the time of egg collection. The time before the start of stimulation can vary. It depends on things like where a woman is in her menstrual cycle. This option may not be suitable for women with cancers such as leukaemia, some lymphomas, and sarcomas as they may need immediate treatment. If you experience OHSS, this may cause a longer delay to the start of cancer treatment.

Will this option affect my chances of the cancer coming back?

There is no data to suggest that embryo freezing affects the chances of cancers growing or coming back.

You may find it useful to write down what you like about this option and what worries you about this option.

These notes may help you talk about whether or not this option is best for you with your cancer care team and fertility care team, partner, family and friends.