A Danish study has reported that ovarian tissue transplants appear to be safe and can restore fertility in women who have undergone treatment for cancer, with around one in three procedures in young women leading to live births.
The study, published in Human Reproduction, reviewed the outcomes of 41 Danish women who had a total of 53 transplantations of thawed ovarian tissue between 2003 and June 2014. Each had been followed for 10 years to assess ovarian function, fertility and the safety of the procedure.
Of the 32 women who had received ovarian transplants to become pregnant, 21 had obtained at least one positive pregnancy test (63 percent). Ten women have given birth to 14 healthy children between them. Eight were conceived naturally, and six as a result of IVF.
'As far as we know, this is the largest series of ovarian tissue transplantation performed worldwide, and these findings show that grafted ovarian tissue is effective in restoring ovarian function in a safe manner. In this series of women, the pregnancy rate was about 30 percent,' said Dr Annette Jensen, from the Rigshospitalet in Copenhagen, Denmark, who worked on the study. 'The fact that cancer survivors are now able to have a child of their own is an immense, quality-of-life boost for them.'
An ovarian transplantation programme has been available in Denmark since 2000. It allows women who are undergoing treatment for cancer, which can damage fertility, to freeze the tissue of one of their ovaries free of charge. The thawed tissue can then be transplanted back, either to the remaining ovary or elsewhere in the abdominal cavity, at a later date. It is hoped that doing so will restore fertility and normal levels of circulating sex hormones, which can prevent menopausal symptoms.
Since its introduction over 800 women have had their ovarian tissue frozen, but the technique remains in its infancy and requires further testing. 'As awareness of quality of life after cancer treatment has increased and techniques for removing, freezing, storing and then transplanting ovarian tissue have developed, fertility preservation is increasingly becoming an integral part of treatment. However, as ovarian transplantation is still in its early days, its efficacy and safety needs to be investigated,' Dr Jensen said.
One of the concerns of ovarian transplantation is that it will cause the cancer that prompted its removal to return. However, the study reported that although three patients did experience a relapse of cancer, none of these were related to the transplantation of ovarian tissue, and therefore the procedure is considered to be safe.
Another risk is presented by radiation to the abdomen, which can increase the risk of miscarriage, premature delivery and stillbirth. The number of women in the study experiencing spontaneous abortions in the first trimester was higher than expected but this is thought to reflect that pregnancy in cancer survivors is more difficult than in healthy women. In addition, there were two abortions and one woman experienced a miscarriage in her 19th week of pregnancy.
The transplanted tissue has been functional for over ten years in three women, eight years in six women, and more than five years in 15 women. The remaining patients have had transplanted tissue for between six months and five years. 'The full functional lifespan of grafts is still being evaluated because many of these women have ovaries that are continuing to function,' said Dr Jensen.
In the UK, ovarian tissue freezing is not currently routinely offered on the NHS. Dr Jensen has said that she hoped the study would 'enable this procedure to be regarded as an established method in other parts of the world'.
Speaking to The Guardian, Grete Brauten-Smith, a clinical nurse specialist at Breast Cancer Care, said: 'Chemotherapy treatment can cause infertility – a massive worry for thousands of younger women with breast cancer. So it is very encouraging to see these improving success rates for freezing ovarian tissue. This could, in future, offer another valuable option for those who face the devastating prospect of not being able to start or add to their family.'