New Frontiers in Fertility Preservation for Women with Cancer
Women of reproductive age who are diagnosed with cancer have several options for preserving fertility. Teresa Woodruff, PhD, Feinberg School of Medicine, Northwestern University in Chicago, discussed new and emerging options in oncofertility at the 2011 American College of Obstetricians and Gynecolo gists meeting. Dr Woodruff had coined the term “oncofertility” and has been a driving force behind the Oncofertility Consortium.
In the United States, 1.7 million females are diagnosed with cancer at age ≤40 years. Aggressive treatments, including chemotherapy, radiation, and surgery, often result in premature menopause. Survivors of pediatric cancers have a 20% reduced chance of becoming pregnant, and young adult survivors have a 50% reduction in the ability to become pregnant. “About 40,000 women each year have childbearing interruptions,” Dr Woodruff noted.
Fertility preservation is an established option for men (including sperm banking, testis biopsy, donor sperm), but women have had fewer choices, although these are now expanding. Hormonal stimulation can achieve oocyte production, and embryos and eggs can be cryopreserved for use when the cancer treatment is completed.
Other options include egg vitrification, ovarian cryopreservation, and adoption/surrogacy. “The frozen embryo is the most mature option we have, but it doesn’t always work,” she said. “Unlike ordinary couples seeking fertility counseling, cancer patients only have a small window of time to undergo fertility preservation procedures. This should be a discussion point with patients.”
Transplanting Ovarian Tissue
Cryopreservation of ovarian tissue is one option for protecting biologic fertility in women. “Unlike men, we have to remove the tissue from the outer layer of the ovary and preserve it,” she explained. This method preserves ovarian follicles at a peripheral storage site for later use, and patients pay a nominal fee for storage each year.
Thus far, 12 live births around the world have resulted from ovarian tissue transplantation in cancer survivors. However, transplanted tissue could harbor some cancer cells, and reimplantation of the tissue could reintroduce the disease after the patient has had curative treatment. This has led to the search for additional methods of fertility preservation that do not entail transplanting the patient’s tissue back into the patient. “In our lab, we are trying to recapitulate folliculogenesis in vitro and eliminate the need for cryogenic storage,” she said.
Dr Woodruff and colleagues are working with a 3-dimensional supportive environment for the ovarian follicle, supported by a material called alginate (derived from algae). Alginate is a gentle jelly mechanism that does not interact with mammalian cells. The in vitro process has spawned live offspring in mice and produced eggs and embryos in nonhuman primates.
The next frontier is humans. They are currently studying in vitro follicle growth using 40 secondary follicles from 19 patients with cancer. “We have gotten good-quality eggs from humans, and we are still tweaking out the optimal physical environment for the human follicle. The next step is to activate the egg. We are not legally allowed to activate human eggs, so this work will need to move forward to a non–federally funded lab or abroad,” she said. “The ultimate objective is to replace the transplant technique, because the tissue can harbor cancer cells.”