By COREY BURKE
Fertility preservation is a term used for protecting or preserving eggs, sperm, embryos, or reproductive tissue so that they may be used in the future to have biological children. Most commonly fertility preservation is associated with cancer treatment, but many other conditions and lifestyles can threaten one's fertility. Endometriosis, uterine fibroids, autoimmune diseases, genetic diseases, toxic exposure, gender reassignment, and hazardous duty (Military) are all reasons to consider fertility preservation.
Cancer survival is at an all-time high for many forms of cancer. The American Cancer Society reports 5-year relative survival rates of 70% for women with Stage 0-III breast cancer with a five-year relative survival rate of close to 100% in women with stage 0 or stage I breast cancer. Far more people are surviving cancer and for many that means the opportunity to start a family and live the life they dreamed of before their diagnosis.
In 2013 the American Society of Clinical Oncology updated their guideline on fertility preservation. The guidance states that caregivers including oncologist, gynecologist, radiational oncologist, urologist, hematologist, pediatric oncologist, surgeons, and others should offer information about fertility preservation to all adult and pediatric patients. It further recommends that if the patient is interested in fertility preservation they should be referred to fertility specialists and that such referrals take place early in the treatment plan. Since this guidance began the number of patients seeking fertility preservation has increased somewhat, particularly in the male population, however it is relatively infrequent that women seek this option.
Several issues may explain the low numbers of women seeking fertility preservation. The procedure in men is far simpler, affordable, requires little time to complete, and usually requires no medications. All the options available to women require significantly more time to complete than men, and costs significantly more. In years past, fertility cycles were initiated based on the women's menstrual cycle which often added weeks to the process. An additional concern was that the process of ovarian stimulation lead to increases in estradiol levels which can drive some tumors. All are valid concerns but can be overcome and should not be a reason for not offering it to a patient. Financial concerns are valid, but options exist including financing. The time to complete treatment and stimulation concerns can be greatly reduced by using mid cycle starts and stimulation protocols to reduce the effects of increased estrogen levels.
What options are available?
Semen cryopreservation is the most effective means of male fertility preservation and is the choice of treatment for most patients. The process is simple, the patient provides a specimen by masturbation and cryoprotectant is added. The specimen is then packaged in straws or vials, slowly chilled to a temperature of -196°C , and stored. Once frozen semen seems to last indefinitely, the oldest specimen used successfully to date being 24 years old. While this option is fast and affordable, physicians should be reminded that one ejaculate is not enough to allow multiple attempts at pregnancy, and patients should be encouraged to provide multiple specimens prior to beginning treatment. To provide optimal results ejaculates should be between 48-72 hours apart. Usually enough semen can be collected in a two-week period to meet the patient's future reproductive goals.
Cryopreservation of testicular tissue is an option for prepubescent boys as well as men who are incapable of ejaculating sperm. Testicular tissue cryopreservation in prepubescent boys is considered experimental and should only be done as part of IRB approved research or a clinical trial.
Gonadal shielding is an option for men undergoing radiation treatment, however cryopreservation is recommended with this option as well.
Women have several options available to them. In the early 2000s a process of "freezing" eggs called vitrification became available to embryologists. Prior to this breakthrough cryopreservation of eggs was difficult and survival rates of eggs post thaw were very poor (30% or less). Freezing a cell involves the formation of ice crystals that can damage and/or kill the cell. Vitrification overcomes this problem by rapidly cooling eggs to -196° C in a fraction of a second. The temperature change approaches - 20,000°C/min and is so rapid it does not allow ice crystals time to form. Survival rates of vitrified eggs are close to 100% and overall IVF success rates are similar to IVF with fresh eggs. The process involves controlled ovarian stimulation, surgical retrieval of the oocytes, vitrification, and storage. Using mid cycle starts the process can be carried out in 3-6 weeks' time.
Embryo creation is an option for women who are married or have a partner. Oocytes are fertilized using the sperm of the patients' partner. Embryos are then cultured in the embryology lab and vitrified using a similar procedure to that of oocytes. The advantage of embryo cryopreservation is that vitrified embryos are easier to warm than eggs because they are multicellular and if a few cells are damaged during warming the embryo will still survive and is usually unaffected by the loss of a few cells.
Ovarian tissue cryopreservation is an experimental procedure with limited results to date. Samples of tissue containing thousands of primordial oocytes are removed from the ovary and cryopreserved. The tissue can later be implanted and hopefully begins to produce mature oocytes that can be harvested and used in IVF to create embryos and ultimately produce a child. So far over 70 pregnancies have been achieved worldwide, but the outlook is encouraging, especially for preadolescent women.
Corey Burke is the Tissue Bank Director of Cryos International - USA. He has 20 years of reproductive laboratory experience and is an industry leader in the field of oocyte and sperm cryopreservation, running one of world's largest donor egg and sperm banks. Working as an andrologist and embryologist, he has helped thousands of people achieve their dreams of becoming parents. Contact at usa@cryosinternational.com
