Cancer patients can now preserve their ability to conceive naturally, with ovarian orthotopic transplant. The Department of Obstetrics & Gynaecology at Singapore General Hospital explains how.
Mdm Tan was in her late 30s when she was diagnosed with breast cancer. Married and childless, her chances of conceiving would become even dimmer with chemotherapy, a treatment she needed to undergo to fight the disease.
In 80 to 100 per cent of women who underwent cancer treatments like chemotherapy and radiotherapy, early menopause and ovarian failure occurred as a result. Even if the ovaries regained their functions after treatment, the woman often experienced difficulty conceiving as the quality of her eggs was often impaired. If she became pregnant, she faced a higher risk of miscarriage or pre-term labour.
Happily for Mdm Tan, she enjoyed better odds, thanks to a new procedure known as ovarian orthotopic transplant.
Ovarian orthotopic transplant
“The procedure involves taking out a part of a woman’s ovary before its functions are damaged. It is then frozen and transplanted back into the woman after her cancer is in remission,” said
Dr Yu Su Ling, Senior Consultant and Director,
Centre for Assisted Reproduction (CARE),
Department of Obstetrics and Gynaecology,
Singapore General Hospital (SGH), a member of the
Mdm Tan had one ovary removed before she started chemotherapy. The ovary was cut into small strips, no wider than 1mm, and then frozen at -200°C, in a process known as cyropreservation. The ovary is cut into such small pieces to allow blood supply to be rapidly restored after the tissue strips are transplanted back into the body.
Transplant of the ovary takes place only after the patient is free of the disease, usually at least two years after the end of the cancer treatment. For Mdm Tan, her cancer was deemed to be in remission last year, and she was cleared for the frozen ovary tissues to be transplanted back into her body.
Before the tissues were inserted back into the body – either into the other ovary (orthotopic) or nearby areas (heterotopic) such as the abdomen – a sample tissue strip needed to be thawed and tested to ensure that it didn’t contain cancer cells.
Three months after her ovarian transplant, the good news arrived. Mdm Tan, who became menopausal after starting chemotherapy, began to have her periods again.
“That means her ovarian transplant was successful,” said Dr Yu.
Ovarian transplant gives hope to female patients in various circumstances
The success of the transplant brings hope for many women patients.
Young women, said Dr Yu, are increasingly affected by diseases or treatments that threaten fertility, like Hodgkin’s lymphoma, breast cancer, endometriosis and cytotoxic treatment. At the same time, better treatment methods mean higher survival rates. For that reason, she added, fertility preservation methods are playing an increasingly important role for these women who want to have children after they are well.
Before this new procedure became available, women who were worried about not being able to conceive after treatment could have their eggs extracted and frozen for in vitro fertilisation (IVF) later. But this option isn’t possible if they need urgent chemotherapy treatment as egg retrieval, including ovarian stimulation, takes about two weeks.
But ovarian transplant doesn’t just address the issue of fertility. For women in their 20s and 30s, the procedure will allow them to delay the onset of menopause. So far, transplanted tissues have been known to function for about seven years, and a transplant of the banked tissues can be done repeatedly. Elsewhere, the banked frozen tissues have been transplanted two to three times.
The first ovarian transplant was performed in 1999, with the first baby born to a woman with an ovarian tissue transplant in Belgium in 2004. There have been at least 20 births worldwide by women who have suffered from cancer and then undergone ovarian tissue transplant.
In Singapore, 13 patients - aged 19 to 40 - have had their ovarian tissues removed and frozen. Mdm Tan is the only one who received a transplant.
Patients pay between $1,600 and $4,000 for the operation to remove their ovaries, and a further $1,800 to $5,500 for the transplant procedure. Patients can claim these expenses from Medisave.
In addition, patients pay about $4,000 to freeze, store and thaw their ovarian tissues. But if it’s successful, a transplant is likely well worth the cost.
Ovarian transplant for cancer patients: how it works
- A suitable patient undergoes keyhole surgery under general anaesthesia to remove one of her ovaries before she starts chemotherapy.
- After removal, the patient’s ovary is cut into small strips of about 1mm in width. This is to enable rapid restoration of blood supply after transplant.
- The pieces are stored in liquid nitrogen at temperatures of almost -200 deg C.
- The transplant of the ovary usually takes place at least two years after the end of cancer treatment, when the risk of relapse is much smaller.
- Before the transplant, one of the strips is thawed and checked for cancer. If there is no trace of malignant cells, the other pieces are thawed. Once thawed, the strips must be transplanted within an hour.
- During the transplant operation, three horizontal incisions are made at the site of the patient’s ovaries. The thawed pieces are inserted through the incisions and the wounds are sutured.
- In Mdm Tan’s case, the ovary that was left in her body was too small to accommodate the many pieces of her preserved ovarian tissues. So, some of the tissues were transplanted into the surrounding area.
- The surgery to remove the ovary takes about an hour, while the surgery to transplant the tissues lasts about 1½ hours.
Pros and cons of ovarian transplant
|Cryopreservation of the ovary can be performed at short notice.||The long-term results are not available as ovarian transplants became available only in 1999.|
|The procedure is fast and easy. It is a day surgery and recovery is within a few days.||Unlike IVF, ovarian transplant involves surgery, which comes with the usual risks and potential complications.|
|Removing the ovary preserves a lot of egg follicles.||There is a risk of re-transplanting the original disease, although stringent measures are in place to ensure there is a minimal risk of transplanting the cancer cells. So, the method is suitable for patients in the early stages of cancer.|
|An ovarian transplant is the best fertility option for very young, single female patients.||Patients should not be too old for fertility reasons. They should be between their late teens and 40.|