FERTILITY PRESERVATION FOR YOUNG WOMEN WITH CANCER
Why fertility preservation?
The chemotherapy and radiotherapy regimes used for many types of cancer, whilst necessary to treat the cancer, can have a toxic effect on the eggs contained in a woman’s ovaries. As women are born with their lifetime number of eggs, these cannot be replaced if damaged. Women who undergo some types of chemotherapy and radiotherapy are therefore at risk of losing their fertility and prematurely becoming menopausal. This risk depends on the age of the woman and the type of therapy they are about to receive, and can be estimated by your specialist.
What can be done?
The four main options for fertility preservation are embryo freezing, egg freezing, ovarian tissue freezing, and medical therapy (GnRH analogues).
Embryo and egg freezing:
For young women with a long term male partner, embryo freezing usually produces the highest chance of preserving fertility. The woman undergoes an IVF cycle with hormonal stimulation to produce a number of mature eggs, and then undergoes an egg collection procedure. The eggs are then mixed with her partner’s sperm to produce embryos in the laboratory, and the embryos are frozen for implantation after the woman has completed her cancer treatments. Using the technique of vitrification (described below), the embryo survives the freezing process over 90% of the time. The chance of a baby from this technique depends on a number of factors such as the age of the woman, these individual chances can be estimated by a fertility specialist.
Egg freezing is a fertility preservation option for women with cancer without a long term male partner. This involves undergoing the start of an IVF cycle as described above, but then the eggs are frozen before the sperm is introduced. Should the woman wish to use these eggs in the future, they are warmed then injected with sperm through a procedure known as ICSI to create an embryo, which is subsequently implanted inside the uterus. Egg freezing is more difficult than embryo freezing for a number of reasons. The egg is the largest cell in the body and contains mostly water. The classic problem with freezing eggs has been that as the temperature drops below freezing point, ice crystals form inside the eggs resulting in structural damage to the egg and its genetic material.
Vitrification is an ultra rapid cooling technique that allows the water inside and surrounding the egg to instantly super cool into a solid state with no ice crystal formation at all. Studies have shown that vitrification results in a higher post-warming survival, fertilisation, embryo development and pregnancy rates than the older, slow-freezing technique. Sydney IVF has many years of experience with vitrification for freezing embryos, and this is now the technique of choice for egg freezing. There have been over 1000 healthy babies born worldwide from egg freezing techniques.
The main disadvantage of both embryo and egg freezing is that it takes some time to stimulate the eggs to maturity (2-4 weeks depending on where you are in your menstrual cycle). Some women may need to start chemotherapy earlier than this. If you are interested in either embryo or egg freezing it is very important that you see a fertility specialist as soon as possible to allow time for these treatments. There are also some side effects of these treatments, which can be further explained by a fertility specialist.
What other options are there?
For women with not enough time to undergo egg or embryo freezing, or who choose not to for other reasons, there are other more experimental techniques available to try to preserve fertility.
One of these techniques is receiving injections or implants of hormones called GnRH agonists, which render a woman temporarily menopausal for the duration of her treatment. It is hoped that this will keep the ovaries in a “quiet” state so that they are less vulnerable to damage by toxic agents. Animal studies have shown promising results and human studies have shown that there is better ovarian function after chemotherapy using this technique. However we do not yet know if the chance of having a baby is improved by using GnRH agonists.
Women undergoing radiotherapy to the pelvic area can have a surgical procedure called orchidopexy, which moves the ovaries to an area of lower radiation exposure.
Finally, there is a technique called ovarian tissue freezing where the woman undergoes keyhole surgery to the abdomen and a piece of ovary is removed for freezing. After chemotherapy, the piece of ovary is then reimplanted back into the ovary, or into another site such as the wall of the pelvis or abdomen. If the tissue is implanted back into the ovary she has a chance of natural conception, but usually she would need to undergo IVF to try to collect the eggs that grow in this piece of ovary. Unfortunately freezing ovarian tissue is even more difficult than freezing eggs so the success with this technique has been very limited.