Fresh and cryopreserved ovarian tissue transplantation for preserving reproductive and endocrine function: a systematic review and individual patient data meta-analysis

BACKGROUND

Ovarian tissue cryopreservation involves freezing and storing of surgically retrieved ovarian tissue in liquid or vapour nitrogen below -190°C. The tissue can be thawed and transplanted back with the aim of restoring fertility or ovarian endocrine function. The techniques for human ovarian tissue freezing and transplantation have evolved over the last 20 years, particularly in the context of fertility preservation in pre-pubertal cancer patients. Fresh ovarian tissue transplantation, using an autograft or donor tissue, is a more recent development; it has the potential to preserve fertility and hormonal function in women who have their ovaries removed for benign gynaecological conditions. The techniques of ovarian tissue cryopreservation and transplantation have progressed rapidly since inception; however, the evidence on the success of this intervention is largely based on case reports and case series.

OBJECTIVE AND RATIONALE

The aim of this study was to systematically review the current evidence by incorporating study-level and individual patient-level meta-analyses of women who received ovarian transplants, including frozen-thawed transplant, fresh or donor graft.

SEARCH METHODS

The review protocol was registered with PROSPERO (CRD42018115233). A comprehensive literature search was performed using MEDLINE, EMBASE, CINAHL and Cochrane Central Register of Controlled Trials from database inception to October 2020. Authors were also contacted for individual patient data if relevant outcomes were not reported in the published manuscripts. Meta-analysis was performed using inverse-variance weighting to calculate summary estimates using a fixed-effects model.

OUTCOMES

The review included 87 studies (735 women). Twenty studies reported on ≥5 cases of ovarian transplants and were included in the meta-analysis (568 women). Fertility outcomes included pregnancy, live birth and miscarriage rates, and endocrine outcomes included oestrogen, FSH and LH levels. The pooled rates were 37% (95% CI: 32-43%) for pregnancy, 28% (95% CI: 24-34%) for live birth and 37% (95% CI: 30-46%) for miscarriage following frozen ovarian tissue transplantation. Pooled mean for pre-transplant oestrogen was 101.6 pmol/l (95% CI: 47.9-155.3), which increased post-transplant to 522.4 pmol/l (95% CI: 315.4-729; mean difference: 228.24; 95% CI: 180.5-276). Pooled mean of pre-transplant FSH was 66.4 IU/l (95% CI: 52.8-84), which decreased post-transplant to 14.1 IU/l (95% CI: 10.9-17.3; mean difference 61.8; 95% CI: 57-66.6). The median time to return of FSH to a value <25 IU/l was 19 weeks (interquartile range: 15-26 weeks; range: 0.4-208 weeks). The median duration of graft function was 2.5 years (interquartile range: 1.4-3.4 years; range: 0.7-5 years). The analysis demonstrated that ovarian tissue cryopreservation and transplantation could restore reproductive and hormonal functions in women. Further studies with larger samples of well-characterized populations are required to define the optimal retrieval, cryopreservation and transplantation processes.

WIDER IMPLICATIONS

Ovarian tissue cryopreservation and transplantation may not only be effective in restoring fertility but also the return of reproductive endocrine function. Although this technology was developed as a fertility preservation option, it may have the scope to be considered for endocrine function preservation.

O-178 Reproductive and endocrine outcomes after fresh and frozen-thawed ovarian tissue transplantation based on age and anti-cancer therapy: A systematic review and individual patient data meta-analysis

Study question

Do reproductive and endocrine outcomes from fresh and frozen-thawed ovarian transplants differ based on age and anti-cancer therapy before cryopreservation?

Summary answer

There was a significant difference in reproductive outcomes of women who have their tissue cryopreserved before or at the age of 35 years.

What is known already

Ovarian tissue cryopreservation (OTC) and transplantation is emerging as a new fertility preservation method. Despite being available for two decades, there is a marked variation in the delivery of this procedure worldwide. Most of the data are based on case reports from specialised centres with expertise in providing this procedure, but there are many unreported cases. Through this review, we aim to collate reproductive and endocrine outcomes from ovarian tissue transplantation. In particular the outcomes in women based on age at cryopreservation and whether they had anti-cancer therapy before cryopreservation were explored.

Study design, size, duration

This study was a systematic review and individual participant level meta-analysis to synthesize the existing evidence on the use of fresh and cryopreserved ovarian tissue transplantation. The review protocol was registered with PROSPERO (CRD42018115233) in November 2018 and the review was concluded in December 2020, including 87 studies (768 women). 

Participants/materials, setting, methods

Literature search was performed using MEDLINE, EMBASE, CINAHL and Cochrane Central Register of Controlled Trials from inception to October 2020. After screening 20,566 abstracts, 87 studies (768 women) were included in the review. Patient-level data was extracted for 388 women and study-level data for 380 women. Authors were also contacted for data if relevant outcomes were not reported in published manuscripts. Meta-analysis was performed using inverse-variance weighting to calculate summary estimates using a fixed-effects model. 

Main results and the role of chance

Age at cryopreservation was provided for 319 out of 388 (82%) women at participant level data. Of these, 283 (88.7%) had ovarian tissue retrieved at ≤ 35 years of age. A subgroup of four studies that reported data on participants age at cryopreservation and transplantation were included in meta-analysis. Pregnancy rates were higher in participants at ≤ 35 years of age at cryopreservation, with results being statistically significant (OR, 0.35; 95% CI: 0.13 to 0.92; z = 2.13; P 0.03, I2= 0%). Return of hormonal function shown as a decrease in FSH (IU/L) was also lower in this group (MD, 4.38; 95% CI: -4.29 to 13.05; z = 0.99; P 0.32, I2= 0%. Whether a participant had received chemotherapy before cryopreservation was explicitly reported in 122 out of 388 (31%) participants and 56 of them (46%) had received anti-cancer treatment before OTC. Thirty-five pregnancies and twenty-four live births were reported in these women. A further meta-analysis from 5 studies showed that although the results were not statistically significant for return of endocrine function, a decrease in FSH, an increase in oestrogen and increased pregnancy rates were noted in participants who did not receive anti-cancer therapy before cryopreservation.

Limitations, reasons for caution

Although we gathered 768 cases of ovarian transplants published in the literature, most were case reports and therefore not included in the meta-analysis. Of the studies included in the meta-analysis, information such as age and anti-cancer therapy were not always provided for individual participants but as an aggregate.

Wider implications of the findings

There was no difference in reproductive and endocrine outcomes for anti-cancer therapy before OTC. Previous chemotherapy alone should therefore not be a deterrent in offering young girls and women OTC. Furthermore, the ideal age to achieve higher pregnancy and live birth rates from OTC is less than 35 years. 

Trial registration number

PROSPERO (CRD42018115233)

Evidence-Based Guideline on Laparoscopy in Pregnancy: Commissioned by the British Society for Gynaecological Endoscopy (BSGE) Endorsed by the Royal College of Obstetricians & Gynaecologists (RCOG)

Laparoscopy is widely utilised to diagnose and treat acute and chronic, gynaecological and general surgical conditions. It has only been in recent years that laparoscopy has become an acceptable surgical alternative to open surgery in pregnancy. To date there is little clinical guidance pertaining to laparoscopic surgery in pregnancy. This is why the BSGE commissioned this guideline. MEDLINE, EMBASE, CINAHL and the Cochrane library were searched up to February 2017 and evidence was collated and graded following the NICE-approved process. The conditions included in this guideline are laparoscopic management of acute appendicitis, acute gall bladder disease and symptomatic benign adnexal tumours in pregnancy. The intended audience for this guideline is obstetricians and gynaecologists in secondary and tertiary care, general surgeons and anaesthetists. However, only laparoscopists who have adequate laparoscopic skills and who perform complex laparoscopic surgery regularly should undertake laparoscopy in pregnant women, since much of the evidence stems from specialised centres.