Fertility preservation for young women facing cancer therapy has garnered endorsements from leading medical groups in oncology and reproductive medicine, and it isn’t in the experimental stages anymore, interviews with experts suggest.
"There is more literature coming out showing that egg freezing does work," said Dr. Clarisa R. Gracia, director of fertility preservation at the University of Pennsylvania Health System, Philadelphia. "We have more data that we can show patients to say, ‘This is not as experimental as it used to be. It is improving, and it is a real option to offer.’ "
Courtesy Dr. Clarisa R. Gracia
Dr. Clarisa R. Gracia
For example, several randomized controlled trials have shown that using frozen eggs is equivalent to using fresh eggs (Hum. Reprod. 2010;25:66-73; Hum. Reprod. 2010;25:2239-46).
The two most common methods of fertility preservation are embryo freezing and egg freezing, according to Dr. Nicole Noyes, a New York City–based reproductive endocrinologist who specializes in infertility, in vitro fertilization (IVF), and egg freezing.
Both procedures involve the use of follicle-stimulating hormone, an injectable medication that causes maturation of multiple eggs in the woman’s ovaries as opposed to a single egg that is naturally ovulated. The stimulated eggs are then gently aspirated from the ovary and placed in a Petri dish.
From this point, either the eggs can be frozen in the unfertilized state or, alternatively, sperm is added, allowing for fertilization and, thus, the creation of embryos prior to freezing. Using either method, eggs or embryos remain cryopreserved until a pregnancy is desired, at which time they are removed from liquid nitrogen for usage. In the case of eggs, fertilization is required post thaw before transfer back to the uterus.
Single girls and women who don’t have a male partner and, thus, don’t have a source of male gamete – other than donor sperm from a bank or "friend" – most often choose egg freezing, whereas women in a committed relationship more often freeze embryos.
"In my patient population, even patients in a committed relationship often choose to freeze some of their gametes unfertilized to increase reproductive autonomy and to lower the relationship pressure – especially given all the stress," she said.
Another fertility preservation option is ovarian tissue freezing, an experimental procedure in which clinicians remove a piece of the ovary via laparoscopy and freeze it. The stored tissue can then be thawed and transplanted back into the pelvis at a later time, in the hope of achieving ovarian function with ovulation and subsequent pregnancy.
"Ovarian tissue freezing is also sometimes offered to prepubertal girls with hopes that it will later function as a source of eggs for that person. To date, there have been no pregnancies or births from tissue transplanted back after being removed at a prepubertal age," Dr. Noyes said.
The advantage of ovarian tissue freezing is that it can be performed in a few hours. The disadvantages are that it requires surgery (general anesthesia and laparoscopy or laparotomy), and there are relatively few successes at this time.
"There have been 17 live births reported worldwide from ovarian tissue freezing and transplantation" in patients who had cancer, Dr. Gracia said "While that’s a limited number, it shows that it can work, and it gives ammunition to keep referring patients to reproductive endocrinologists who are involved in fertility preservation and who are aware of what’s available."
Timing and Cancer Type Are Critical
Young women with breast cancer, gynecologic cancer, or a hematologic malignancy are the patients most often seeking fertility preservation, said Dr. Noyes. It takes an average of 17 days from the day of consult with a reproductive endocrinologist to the day of oocyte retrieval, and this can be an obstacle.
"For some malignancies, that’s too long to wait, such as for hematologic malignancies including non-Hodgkin’s lymphoma – the really sick patients who have a full tumor load," she said.
"In breast cancer cases, we generally do oocyte retrieval between surgery and chemotherapy. There’s usually a 4-6 week window there, so that usually is not an issue. The problem is, sometimes the oncologist doesn’t call you until they’re 5 weeks after their surgery to ask if you can do the oocyte retrieval in 7 days."
Bone marrow transplant patients face almost a 100% chance of ovarian failure from the pretreatment for the transplant. "Those patients are great candidates for fertility preservation," Dr. Noyes said. "Any regimen that has an alkylating agent such as cyclophosphamide (Cytoxan), those patients are at high risk. Almost all breast cancer patients get Cytoxan."