Ovarian tissue cryopreservation

Dr Chris Venter expands on ovarian tissue cryopreservation – a novel fertility preservation technique for selective clinical cases.

Early cancer detection and advances in chemotherapeutic treatment regimens have led to a dramatic increase in cancer survivors. 

A large proportion of these survivors are women of reproductive age. Research has shown that one of the major concerns in these cancer survivors is the impact of cancer treatment on their reproductive health. 

Fertility-risk assessment and counselling prior to chemotherapy is steadily becoming the standard of care in South Africa. This is in keeping with a holistic approach to the needs of the patient and future quality of life. 

As more patients are being referred, clinical challenging cases will present themselves. 

The most commonly accepted techniques of fertility preservation remain embryo and oocyte (a cell in an ovary) cryopreservation. These options require post-pubertal females with a 10 – 12-day window to allow for ovarian stimulation and maturation of eggs.

But what would the option be when faced with a pre-pubertal girl or a patient whose chemotherapy is time-sensitive. For example, a young pre-pubertal girl with a haematological condition who requires an autologous stem cell transplant, or a post-pubertal breast cancer patient who couldn’t delay initiation of chemotherapy. 

For these patients, ovarian tissue cryopreservation (OTC) remains the only fertility preservation option.

Ovarian tissue cryopreservation 

Ovarian tissue cryopreservation has been regarded as an experimental procedure for several years, but mounting clinical evidence has challenged this status recently. The United States and some European countries have now removed this experimental status. Therefore, offering this fertility preservation option to pre-pubertal females and post-pubertal females with aggressive malignancies where there is insufficient time to allow for ovarian stimulation.

OTC technique

The outer part of the ovary consists of thousands of young immature eggs. The younger the patient, the higher the number of eggs on this outer surface. 

Retrieving ovarian tissue is managed by performing minimal invasive surgery via a laparoscopy. This is an operation performed in the abdomen or pelvis using small incisions with the aid of a camera. 

During the procedure, a part of the one ovary is removed, and grafted into small pieces. Should the chemotherapy have a high likelihood of complete loss of ovarian function then more ovarian tissue should be removed. These ovarian grafts will then be cryopreserved. 

Should the patient in years to come develop premature ovarian failure due to the gonadotoxic effects of chemotherapy, these grafts could be re-implanted back into the pelvis, usually in the area of the ovary. This is also performed laparoscopically.

How effective is OTC treatment?

It has been observed that the ovarian function usually resumes within 60 – 240 days of implantation, and that every graft procedure can last up to five to seven years. The reported pregnancy rate among patients who opted for this procedure is 29%. Worldwide, there has been over 130 live births reported from this procedure. 

It is also important to note that besides the reproductive advantages of this procedure, it also has the additional benefit of establishing a normal hormonal status in patients who have previously experience menopausal symptoms. 

Historically, there is limited use of this procedure in South Africa. Although, we have one recorded pregnancy, and as the experimental status is lifted more pregnancies will follow.

Risk of the OTC procedure

This procedure is contra-indicated in patients who have a high risk of ovarian metastasis or where a blood-borne cancer, like leukaemia, could be present in the ovary. Re-implantation of potentially affected ovarian tissue could lead to reseeding of the cancer. 

A laparoscopy, although minimal invasive, does also have procedural risk. Informed consent, or assent in the case of a minor is essential, and special reference to limited data of the procedure should be recorded in the consent. 

Final thought

Overall, the data on the efficacy, safety and reproductive outcomes after OTC are still limited. Therefore, OTC should only be offered to carefully selected patients who are at high risk of ovarian failure due to their gonadotoxic treatment. Lastly, only reproductive centres who have the necessary surgical and vitrification expertise should offer this service.