Comparing Fertility Preservation Options for Cancer Patients: Egg Freezing, Embryo Freezing, and Ovarian Tissue Freezing

Table of Contents

• Introduction: Why Fertility Preservation Matters for Cancer Patients
• How the Research Was Conducted
• Detailed Results: Pregnancy, Birth, and Miscarriage Rates
• What These Findings Mean for Patients
• Study Limitations and Considerations
• Patient Recommendations and Next Steps
• Source Information

Introduction: Why Fertility Preservation Matters for Cancer Patients

Fertility preservation has become a critical quality-of-life issue for cancer survivors who wish to have children. As cancer treatments have dramatically improved over recent decades, more people are surviving their diagnoses but facing the lasting side effects of treatment, including infertility. In England today, more than half of people diagnosed with cancer will survive for 10 or more years - a twofold improvement since the 1980s.

Infertility resulting from cancer treatment can lead to depression, anxiety, and reduced quality of life. Modern medical guidelines recommend that women should be offered specialist fertility counseling and fertility preservation options before beginning cancer treatment. The choice between different preservation methods depends on multiple factors including patient age, cancer type and prognosis, ovarian reserve, treatment regimen, and how much time is safely available before treatment must begin.

This research specifically addresses a significant gap in knowledge: which of the three main fertility preservation methods - egg freezing (oocyte cryopreservation), embryo freezing (embryo cryopreservation), or ovarian tissue freezing (ovarian tissue cryopreservation) - offers the best chances of successful pregnancy and live birth for cancer patients who later wish to start a family.

How the Research Was Conducted

Researchers conducted a comprehensive systematic review and meta-analysis following established PRISMA guidelines. They searched three major medical databases - Embase, Medline, and Web of Science - identifying 5,308 records initially, with 1,270 duplicates removed, leaving 4,038 unique entries for evaluation.

The study inclusion criteria were specific and rigorous. Researchers only included studies that involved women at risk for infertility due to medical treatment that could damage reproductive cells (gonadotoxic therapy), who had completed one of the three cryopreservation procedures, and who had documented follow-up including reproductive outcomes. All included studies needed to contain original data.

The team excluded studies where pregnancy was attempted using methods other than the cryopreserved materials, such as fresh IVF cycles, donor eggs, or natural conception in cases of egg or embryo freezing. They also excluded fertility preservation approaches consisting only of conservative surgery or ovarian suppression, cases using in vitro matured eggs, surrogacy arrangements, and gender transition-related preservation.

After thorough screening, 38 studies met all inclusion criteria and were analyzed in detail. These studies represented a mix of retrospective and prospective observational research. The quality assessment using the Newcastle-Ottawa scale found that 21 studies were of good quality, 10 were fair quality, and 8 were poor quality.

The research team extracted comprehensive data from each study, including: number of participants who completed fertility preservation, average age at time of preservation, preservation method used, cancer diagnosis, history of previous chemotherapy or radiation exposure, number of patients who returned to use their preserved materials, total number of transfer or transplant procedures, clinical pregnancy rates, live birth rates, and miscarriage numbers.

Detailed Results: Pregnancy, Birth, and Miscarriage Rates

The analysis included data from 170 women who returned to use frozen eggs, completing 178 transfer procedures, and 75 women who returned to use frozen embryos, completing 102 transfer procedures. For ovarian tissue preservation, the 550 transplants represent the number of surgeries performed rather than individual tissue pieces, as some women required multiple surgeries when menstrual cycles didn't return or ceased after some time.

Clinical Pregnancy Rates: The analysis found clinical pregnancy rates of 34.9% for egg freezing, 49.0% for embryo freezing, and 43.8% for ovarian tissue freezing. These results mean that approximately 35-49% of transfer or transplant procedures resulted in confirmed pregnancies with detectable fetal heartbeat. Statistical analysis found no significant differences among these three groups.

Live Birth Rates: Perhaps the most important outcome for patients, live birth rates were 25.8% for egg freezing, 35.3% for embryo freezing, and 32.3% for ovarian tissue freezing. Again, statistical analysis showed no significant differences among the three methods, indicating that all three approaches offer similar chances of successfully having a baby after cancer treatment.

Miscarriage Rates: This is where the research found a significant difference. Miscarriage rates were 9.2% for egg freezing, 16.9% for embryo freezing, and 7.5% for ovarian tissue freezing. The analysis revealed significantly fewer miscarriages with ovarian tissue preservation compared to embryo preservation. This finding is particularly noteworthy given that ovarian tissue preservation is still considered experimental in many regions.

The statistical tests for heterogeneity (variation between studies) showed consistent methodologies for egg and embryo freezing studies but significant variation in ovarian tissue studies, which is expected given that this technique is newer and practices may differ more between medical centers.

What These Findings Mean for Patients

This research provides crucial evidence-based information for cancer patients facing difficult decisions about fertility preservation. The most significant finding is that all three methods offer similar success rates for achieving pregnancy and live births, which means patients can choose based on their personal circumstances rather than perceived effectiveness.

For patients who cannot delay cancer treatment, ovarian tissue preservation emerges as a particularly valuable option. Unlike egg or embryo freezing, which require 2-3 weeks of ovarian stimulation before treatment can begin, ovarian tissue preservation requires no stimulation and can be performed immediately. This method also doesn't require a male partner or sperm donor, preserving future reproductive autonomy.

The significantly lower miscarriage rate with ovarian tissue preservation (7.5% compared to 16.9% with embryo freezing) is an important consideration, especially for patients who have experienced pregnancy loss or have concerns about miscarriage risk. This finding challenges the perception that newer preservation methods are less effective.

For young girls who haven't reached puberty, ovarian tissue preservation is currently the only available option, as egg and embryo freezing require mature reproductive systems. The research confirms that this method can offer future fertility opportunities for pediatric cancer patients.

The fact that ovarian tissue preservation allows for the possibility of natural conception (without IVF) represents both an emotional and financial benefit for patients, potentially reducing the substantial costs associated with fertility treatments after cancer recovery.

Study Limitations and Considerations

While this research provides valuable insights, several limitations must be considered when interpreting the results. The most significant limitation is the low utilization rate - only 5% of women with frozen eggs, 10% with frozen embryos, and 6.7% with ovarian tissue returned to use their preserved materials. This means we have outcome data for only a small percentage of patients who undergo fertility preservation.

There are multiple reasons for this low return rate. Many patients may postpone family planning after cancer treatment due to concerns about lower conception rates and increased risk of preterm birth when attempting pregnancy soon after chemotherapy. Patients with certain cancers like breast cancer may be advised to take tamoxifen for 5-10 years after diagnosis, which carries fetal malformation risks if taken during pregnancy.

The studies included in this analysis showed significant methodological variation, particularly for ovarian tissue preservation. This technique is still evolving, and practices differ between medical centers, which may affect outcomes. Additionally, the analysis couldn't account for differences in cancer types or previous exposure to chemotherapy or radiation, as not all studies reported this information comprehensively.

Another important consideration is the risk of reintroducing cancer cells with ovarian tissue transplantation, particularly for cancers that metastasize easily such as blood cancers and ovarian cancers. This risk must be carefully evaluated for each patient before choosing ovarian tissue preservation.

Finally, the research didn't distinguish between patients who underwent controlled versus random-start ovarian stimulation protocols before egg or embryo freezing, though emerging evidence suggests little difference in outcomes between these approaches.

Patient Recommendations and Next Steps

Based on these findings, patients facing cancer treatment should consider the following recommendations when making fertility preservation decisions:

1. Discuss all options with a fertility specialist before beginning cancer treatment. The similar success rates mean your personal circumstances should guide your choice rather than perceived effectiveness.
2. Consider time constraints carefully. If your cancer treatment cannot be delayed, ovarian tissue preservation may be your best option as it requires no ovarian stimulation period.
3. Think about future family planning. If you don't have a partner or don't want to use donor sperm, egg or ovarian tissue freezing preserves more reproductive autonomy than embryo freezing.
4. Ask about miscarriage risks. If you have concerns about pregnancy loss, the significantly lower miscarriage rate with ovarian tissue preservation may influence your decision.
5. Inquire about experimental status. While ovarian tissue preservation showed excellent results, it's still considered experimental in some regions, which may affect insurance coverage and availability.
6. Consider long-term timing. Many cancer survivors wait years before attempting pregnancy due to treatment follow-up requirements, so think about how this might affect your preservation choices.

Patients should also ask their medical team about:

• The center's experience with each preservation method
• Success rates specific to their cancer type and age
• Any additional risks associated with each option
• Financial considerations and insurance coverage
• Long-term storage options and costs

Source Information

Original Article Title: "A comparison of fertility preservation outcomes in patients who froze oocytes, embryos, or ovarian tissue for medically indicated circumstances: a systematic review and meta-analysis"

Authors: Bríd Ní Dhonnabháin, M.Sc., Nagla Elfaki, MD., Kyra Fraser, M.Sc., Aviva Petrie, Ph.D., Benjamin P. Jones, M.R.C.O.G., Srdjan Saso, Ph.D., Paul J. Hardiman, Ph.D., and Natalie Getreu, Ph.D.

Publication: Fertility and Sterility, Volume 117, Issue 6, June 2022, Pages 1266-1276

Note: This patient-friendly article is based on peer-reviewed research originally published in a scientific medical journal. It preserves all numerical data, statistical findings, and conclusions from the original study while making the information accessible to non-medical readers.