Fertility Q&A Ovarian Tissue Freezing
If you are preparing to undergo cancer treatment, you may already be aware that cancer therapies—including chemotherapy and radiation—can cause infertility and premature menopause. If having children after completing your cancer treatment is important to you, you may have begun to consider options for fertility preservation. Because your chance of future successful pregnancies is best when fertility preservation procedures are performed before chemotherapy or radiation, the amount of time available to pursue these procedures is often limited and depends on when your cancer treatment is scheduled to start.
Embryo freezing is the most proven method of fertility preservation and is an excellent option for women who are married, have a male partner, or are interested in using donor sperm. It typically requires 10 to 14 days from the beginning of a menstrual period to allow for hormonal injections, which are necessary to stimulate growth of mature eggs.
For patients whose cancer therapy cannot be delayed for 10 to 14 days or more, ovarian tissue freezing is an alternative strategy for fertility preservation, intended mostly for cancer patients who have a high risk of premature menopause after cancer treatment (for example, bone marrow transplant patients, women 35 years and older, and recipients of high-dose alkylating agents).
Ovarian tissue containing immature eggs can be removed by a minor surgical procedure (called laparoscopy) and preserved for future use. Although ovarian tissue freezing is still considered experimental, its distinct advantages have led to increasing use of this technology and promising results in recent years. It is the only option available for prepubertal girls, and it may be the best option for patients who cannot delay the start of their chemotherapy or radiation because it does not require time for ovarian stimulation. The surgical removal of ovarian tissue causes no delay in cancer treatment initiation and yields an abundance of immature eggs. For any of these eggs to produce a pregnancy, they must first become mature—a process that can occur inside the body (in vivo) or in the laboratory (in vitro).
Thus far the most successful way to use the frozen ovarian tissue to achieve pregnancy is to reimplant thawed pieces of the ovary back into the body (auto-transplantation) once you have completed cancer treatment, are disease-free, and are ready to become pregnant. Auto-transplantation requires an additional surgical procedure, but it allows the body to go back to ovulating naturally and, in some cases, conceiving naturally. Eighteen live-born babies have been reported worldwide as a result of this technique, suggesting that it may be a good option for those who cannot pursue embryo freezing.
One of the main concerns of transplanting thawed ovarian tissue into cancer patients in remission, however, is the potential for the reintroduction of malignant cells, which could theoretically propagate cancer recurrence. Although there are no reports of recurrences from this procedure in humans so far, animal studies have found that recurrences are a possible consequence of ovarian tissue transplantation, especially in cases of leukemia.
To avoid the potential risks associated with reimplanting the ovarian tissue, researchers are studying other methods of utilizing the tissue to achieve pregnancies. Though the frozen ovarian tissue contains many eggs, the eggs are immature and are unable to be fertilized or result in pregnancy. Techniques to mature the eggs in the laboratory (in vitro maturation) have been developed and refined over the past several decades, leading to consistent improvements in egg survival and fertilization. Recent reports of pregnancies and healthy live-born babies resulting from this technology in women without cancer, as well as the successful freezing of eggs matured in the laboratory in women with cancer, indicate that this strategy holds promise for fertility preservation in female cancer patients. Therefore, ovarian tissue freezing can be considered an option for those patients who cannot or do not wish to delay their cancer treatment.
If you are considering having children after completing your cancer treatment, be sure to speak with your oncologist about your fertility questions as soon as possible—and before beginning treatment. Because the impact of cancer treatment on a woman’s fertility varies from individual to individual, it is important to understand the risks and the options specific to your situation. For many women, consulting a fertility specialist and undergoing a fertility preservation procedure prior to the initiation of cancer treatment is an excellent choice.
Karine Chung, MD, MSCE, is one of three physician partners at USC Fertility (USCF), the not-for-profit private fertility practice of the University of Southern California, Los Angeles. She is also the founder and the director of USCF’s Fertility Preservation Program for cancer patients. For more information please visit www.uscfertility.org or www.uscfertilitypreservation.org.