Fertility Preservation Flashcards
1
Q
Why is fertility preservation needed?
A
- Cancer, radiotherapy & chemotherapy can cause premature gonadal failure. Associated somatic disorders such as fever, malnutrition, anxiety or depression may affect fertility.
- 20% of patients with premature ovarian failure have an autoimmune associated disease such as diabetes, thyroid dysfunction, Addison syndrome, Crohn’s disease etc.
- Surgery, endometriosis, infection, family history of premature ovarian failure & idiopathic causes.
- Women delaying child bearing due to social factors. Advanced maternal age; women can preserve their eggs when they’re young.
2
Q
Why is there a focus on fertility in cancer?
A
- The main reason for intervening and preserving fertility is cancer.
- Half of people diagnosed with cancer now survive their disease for at least five years - cancer survival rates in the UK have doubled in the last 40 years.
- Almost three-quarters of children are now cured of their disease, compared with around a quarter in the late 1960s.
- Cancer therapy can result in infertility or premature gonadal failure leading to a significant quality of life issue for young survivors.
- Approximately 75% of patients under 35 who are childless at the time of cancer diagnosis desire children in the future.
- Young patients tend to be treated aggressively, as they can withstand a lot of chemotherapy, so this can damage their fertility.
3
Q
How may surgery lead to infertility?
A
1) Males
- Unilateral orchidectomy (removal of the testes) reduces sperm concentration. Reduced spermatogenesis is reversible within the first year after surgery. Removing one testis may cause slightly reduced fertility output and then it returns to normal (only really need one).
- Retroperitoneal lymph node dissection can cause serious disruption of ejaculation (testicular or renal cell carcinoma), e.g. disrupting the nerve supply.
- Radical prostatectomy, e.g. in prostate cancer, may lead to erectile dysfunction, retrograde ejaculation and poor semen quality.
- Rectal cancer surgery may lead to erectile dysfunction (can interfere with the responsible nervous supply).
2) Females
- Hysterectomy (removal of the uterus) or oophorectomy (removal of the ovaries) may be performed. Sometimes try to maintain one ovary, but depends on the chances of ovarian cancer.
- In some women with early stage ovarian or cervical cancer it is appropriate to attempt to retain one ovary, both for future fertility and hormone production.
- Patients with small cervical cancers may undergo trachelectomy, which removes the cervix but leaves the uterus in-situ.
- Sometimes surgery can cause scarring in the uterine tubes which may obstruct them. Surgery in the pelvis can cause inflammation, surgical adhesions, scarring etc. that can block the uterine tubes.
4
Q
How may radiotherapy lead to infertility?
A
- Varying amounts of infertility dependent on doses (measured in grays) and where the radiation is going.
- Cells are particularly susceptible to these radiotherapy techniques (radiation damage) while they are dividing. Once they unravel their DNA to divide, they become very sensitive. The tumours divide more rapidly than most cells in the body, so they are targeted by irradiation. The radiation is targeted to the area of the tumour.
- Important to remember with radiotherapy that some of the radio waves may reflect off surfaces, such as bones.
- Head and neck tumours, e.g. tracheal or thyroid tumour, can interfere with the HPG axis. This can lead to infertility (doesn’t have to be the gonads themselves)
1) Males
- Irradiation in the G2 phase of the cycle induces chromatid aberrations. Analyse dose/response of peripheral blood cells, enabling restriction of dose.
- 0.5 Gy = Transient suppression with subsequent recovery of spermatogenesis.
- 2–3 Gy = Period of azoospermia after which full recovery is expected within three years.
- 4–6 Gy = Recovery is not universal and may take up to five years.
- 6 Gy = High risk of permanent sterility.
- Total body irradiation (TBI), e.g. for leukaemia, with high-dose chemotherapy will sterilise men.
2) Females
- Ovarian damage depends on patients age, dose & field of irradiation. Radiation to the pelvis can have a direct negative impact on ovarian function and the uterus by altering vascularisation.
- Doses of 4-6 Gy can produce a loss of 50% of the follicle population.
- Total body irradiation (typically 10-12 Gy) causes infertility, recovery of ovarian function occurs in 10-15% of cases.
- Non-pelvic radiation, especially head and neck may disrupt the hypothalamic-pituitary axis.
5
Q
What are the effects of chemotherapy on the ovary?
A
- Cyclophosphamide is one of the alkylating agents that has been used for many years. With increasing doses in mg/kg, the effect on fertility can be seen on this graph. No. of surviving primordial follicles following exposure correlates inversely to dose of chemotherapy (Meirow et.al. 1999).
- When saying a women stops ovulating and enters menopause, it does not mean there are no follicles left; there is a critical number below which a women stops ovulating.
- Can push a lot of women over the edge depending on what they start with
6
Q
What are the patient’s psychological concerns and reactions?
A
- Digesting the ‘double blow’. Bewildered and overwhelmed.
- Feelings of being ‘out of control’ and struggling to regain a sense of personal stability.
- Sense of being robbed of one’s manhood or womanhood.
- Grief over the possible loss of the opportunity to fulfill one’s dreams.
- Anger toward the medical community for failing to provide adequate information regarding fertility risks.
- Not every oncologist will have this discussion; some are focussed on curing the cancer, depends on the level of knowledge of the oncologist (what the options are, what to say etc.).
7
Q
What fertility preservation options are available?
A
- In pre-pubescent / adult males, there is testicular tissue cryopreservation (experimental) = Surgical removal of testicular tissue and maturation in-vitro/autotransplantation, which will take a day. This is the idea that a biopsy could be taken, could freeze some of the seminiferous tubules and later retransplant them back. The question is whether there is normal ejaculation or sperm is collected with a needle.
- In adult males, sperm can be collected via masturbation and frozen before treatment (sperm cryopreservation). Relatively straightforward; < 1 week (3 collections x 48h).
- In pre-pubescent/adult females, there is ovarian tissue cryopreservation = Surgical removal of ovarian tissue and later autotransplantation; 1 day
- In adult females, there are several options. In-vitro maturation of oocytes/follicles involves collection of immature oocytes and maturation in-vitro; 1 day. Another option is oophoropexy, which involves surgical relocation of ovaries outside radiation field (1 day). Ooctye/ Embryo cryopreservation is another option where there is controlled ovarian stimulation / oocyte retrieval followed by IVF; 2-3 weeks. Administration of suppressive agents can also be used in ovarian suppression; immediate.
- The main option is an IVF cycle and freezing the oocytes (oocyte/embryo cryopreservation). Others have tried suppressing the ovaries using GnRH while undergoing treatment. The theory is that there is less damage when the ovaries are quiescent (not much evidence to support this). In vitro maturation of follicles involves growing follicles in the lab at whatever stage they are found. Moving the ovaries outside of the radiation field has also been tried.
8
Q
What is oocyte cryopreservation?
A
- Controlled ovarian stimulation using gonadotrophins for 8-12 days followed by oocyte retrieval. Can carry out the IVF cycle, collect oocytes and freeze them so that they are ready for when the patient recovers (then continue with IVF). Alternatively, it is a bit more reliable to freeze embryos. When the patient has a partner/donor sperm, the embryos can be frozen and kept until the patient recovers.
- Difficulties with slow freezing – ice crystal formation, low survival and poor embryo quality. Now becoming routine practice in IVF centres with the development of oocyte vitrification. It used to be difficult to freeze eggs, because they are large with lots of cytoplasm; ice crystals form and damage the internal architecture of the egg (like freezing a strawberry). A new technique was then invented to make this possible; vitrification involves freezing so fast that there is no time for ice crystal formation.
- Suitable strategy for patients who can postpone oncologic treatment and where COS is not contraindicated.
- Valid option for post pubertal women without a male partner or those who do not want donor sperm or object to embryo cryopreservation.
9
Q
What are the disadvantages of oocyte cryopreservation?
A
- The entire process takes a minimum of 2-3 weeks depending upon the patients menstrual cycle.
- Exposure to high levels of estradiol is contraindicated. There is controversy on this issue with some authors arguing that a short-term increase is not harmful.
- Ovarian stimulation protocols including aromatase inhibitors have been described in order to avoid excessive high estradiol levels.
- There are two problems with this. Firstly, the process will take two to three weeks. If the patient has a very aggressive tumour, the oncologist may say it is not possible to wait for a few weeks. Also, some tumour cells contain oestrogen receptors. They are very common in breast cancers (the most common cancer in women). If the tumour is oestrogen receptor positive, growing 12 to 15 follicles will cause high oestrogen levels. If the tumour has oestrogen receptors, the oestrogen produced will stimulate growth of the tumour. The oncologist may decide that either the time or the oestrogen levels associated with an IVF cycle cannot be permitted.
10
Q
What is embryo cryopreservation?
A
- Most standardised procedure
- High embryo survival and cumulative pregnancy rates of 60%. It is easy to freeze the embryos; you know what you have (don’t know how good the eggs are until they are embryos).
- Requirement for male partner or sperm donor.
- Ethical implications of increasing numbers of embryos stored in IVF clinics make oocyte vitrification a preferred option in many cases.
- As some women may die, there are ethical implications regarding what happens to the embryos.
11
Q
What is in-vitro maturation of oocytes?
A
- Retrieval of immature oocytes followed by in-vitro maturation.
- A less traumatic/invasive technique would be quite good if available oocytes could be extracted and grown in vitro so they are ready for ovulation.
- One of the strategies in cases where ovarian stimulation is not possible.
- Oocyte retrieval usually performed prior to ovulation, but immature oocytes can be recovered during both follicular and luteal phases.
- Vitrification of IVM oocytes has resulted in live birth rates <20%. Survival and fertilisation rates lower than for oocytes matured in-vivo.
- A woman may have a few follicles at various levels of development. This idea has been tried and there have been pregnancies from oocytes taken that were nearly mature. The idea that immature oocytes can be taken from the ovaries and cultured up until maturity has not yet been realised. Right now, an oocyte that is a day or two away from ovulation can be pushed over the line in order to carry this out, but even then it is experimental (has been done). Lots of research is being carried out to look into using more immature oocytes.
12
Q
What is in-vitro follicle culture?
A
- Proposed as an alternative to IVM, the aim being to develop an in-vitro system that allows growth of primordial follicles to antral stages in order to obtain mature oocytes.
- Given the complexity of folliculogenesis, much research into culture conditions is still necessary in order to achieve results for clinical practice.
- Here, the idea is removing a whole follicle rather than just the oocyte. Can 3D culture the entire follicle; Can take follicles of different ages in a few hours, grow the follicles up and freeze the eggs obtained from them. A lot of research is going into it, e.g. what are the right culture conditions, how do you do a 3D culture of a follicle? It is a great vehicle for research.
- At the moment, the oocyte culture is doing a bit better than this. It is still a way off before this can be carried out. This is not really an option, it is more of an experimental one for the future.
13
Q
What is ovarian tissue cryopreservation?
A
- Removal of an ovary and cryopreservation of cortical fragments. Fragments may be autotransplanted after recovery.
- Primordial follicles are relatively resistant to cryopreservation injury. Despite this a high loss of follicles may occur during the ischemic period until revascularisation is established.
- Because of the lack of a world-wide registry the effectiveness of the technique has not been quantified. However, the leading groups report encouraging success rates.
- One concern is the risk of re-seeding malignant cells – the technique is contraindicated in leukaemias.
- Some of the ovary can be removed, frozen and transplanted back to them once the patient has recovered.
The primordial follicles are halfway through meiosis I; they’re not that active and they’re quite resilient. They don’t have an antrum or much fluid within them, so they are quite resistant to the traditional freezing process. One ovary can be removed, the outside (cortex of the ovary) can be taken away, it can be chopped into pieces and frozen. When the patient gets better, those pieces can be transplanted back into the patient (their own ovary). The pieces have to be the right size and volume. This has another advantage = one follicle in the ovary each month is the entire endocrine system in the ovary. All of the oestrogen and the progesterone throughout the whole menstrual cycle comes from that one follicle within the ovary. When transplanting ovarian tissue back into the patient, not only does she get a chance of being fertile again, but she also gets her reproductive menstrual cycles back (rather than being menopausal). - An ovary is removed, frozen, treatment takes place and if the woman becomes menopausal following treatment, pieces of her ovary can be transplanted back. She gets her cycle back and can get pregnant again.
- Only option for pre-pubescent girls and women who cannot delay cancer treatment or undergo controlled ovarian stimulation. Prepubertal girls who haven’t started to menstruate can’t be given an IVF cycle. If ovarian tissue is taken from them, it could be used to help them introduce puberty later if they needed it.
- Transplants of cortical fragments can be done
1) orthotopically – contralateral ovary
2) heterotopically – eg. peritoneal cavity - Neoangiogenesis is still the limiting factor as it takes up to 5 days and leads to some loss of primordial follicles. Pregnancies reported to date have been both spontaneous and after IVF.
14
Q
How is a laparoscopic oophorectomy carried out?
A
- Oophorectomy = removal of the ovary.
- This is how the ovary is removed.
- Three, pencil-sized holes are made in the abdomen. Through one of them, a camera with a light goes through. Through the other one, there’s a scalpel (or scissors) and through the third one, there is a plastic bag. The ovary is resected, placed in the plastic bag and pulled out of the hole.
This is a laparoscope through a tiny incision. The patient is not opened up.
15
Q
How is ovarian tissue frozen?
A
- The pieces have to be the right size and volume.
- They are first incubated for 30min @ 1◦C with cryoprotectant (a kind of antifreeze solution) to stop or delay the formation of ice crystals as they freeze. Too much antifreeze will kill the tissue, too little antifreeze will cause ice crystal formation which will also kill the tissue.
- Increasing concentrations of cryoprotectant before freezing them.
- Freezing cycle
1) 2°C/min to -9°C
2) 5 min of soaking
3) Manual seeding for ice crystal nucleation induction 2-3 seconds
4) 0.3°C/min to -40°C
5) 10°C/min to -140°C
6) Plunge into liquid nitrogen at -196°C - This machine causes a slow freezing protocol, taking them down to -196°C. Once they are at -196°C in liquid nitrogen, they can be stored almost indefinitely (much longer than the life of the patient at least). They are kept in liquid nitrogen dewars.
