In vitro maturation for cancer patients
A baby has been born to an infertile cancer survivor, after immature eggs were removed from her body before treatment, matured in a lab, frozen for five years, then thawed and fertilized.
It's not easy for any young person to hear they have cancer and should freeze their gametes just in case. But it's especially not easy when that young person is a woman. Preserving eggs is a complicated and arduous business, and there's a lot to consider when you are simultaneously dealing with cancer.
Below I summarize details of the first successful birth to a cancer survivor using a technique that allows preservation of eggs without the burden of ovarian stimulation.
A new option for preserving fertility
Women who face cancer treatment before they have completed their families may have a new option for preserving their fertility. It involves removing immature eggs, maturing them in a laboratory, freezing them, then thawing them when the woman is ready to become pregnant.
The technique is known as "in vitro maturation" (IVM) and has already led to the births of about 5000 babies worldwide. What is new this time is that the baby was born to a former cancer patient after the artificially ripened eggs spent five years in the deep freeze.
The technique is important for cancer patients for two reasons, wrote Michael Brynberg, at Antoine Beclere University Hospital near Paris, in a report published last month in the journal Annals of Oncology. Brynberg managed the fertility preservation of the woman featured in the report.
One is that cancer patients sometimes don't have time to go through the process of ovarian stimulation — the first step in conventional IVF — which involves using hormone drugs to coax the ovaries to produce more than the usual one mature egg. So, rather than mature the eggs inside the body, IVM extracts them early and matures them on the outside, in a laboratory. (Both IVF and IVM exploit the fact that each month, several immature eggs vie to be the one brought to maturity; both techniques involve maturing what would otherwise be discards.)
Another concern for cancer patients is that the drugs used in ovarian stimulation could worsen the cancer.
Both were considerations for the woman in this case, who was diagnosed with stage III breast cancer at age 29 and started chemotherapy three weeks later.
The woman was also offered the option of having some ovarian tissue removed and preserved. She declined that offer, however, because, according to Brynberg, she felt it would be too invasive right after receiving her diagnosis. Additionally, cancer patients are often concerned that transferring tissue back into their bodies after successful treatment could inadvertently reintroduce cancer cells.
An ultrasound indicated the woman had 17 follicles containing immature eggs; the physician was later able to retrieve seven of them. The immature eggs were placed into a special IVM medium and supplemented with serum from the woman's blood, along with follicle stimulating hormone (FSH) and human chorionic gonadotropin (HCG). After 48 hours, six of the seven eggs had reached maturity, and were vitrified using liquid nitrogen.
Five years later, in good health, the woman found she could not get pregnant after a year of trying. She was concerned that stimulating her ovaries might cause a recurrence of her breast cancer, according to the report, so she opted to use her frozen IVM eggs.
All six eggs survived thawing and they were fertilized with intracytoplasmic sperm injection (ICSI). Five fertilized successfully. One was transferred to her uterus, which had been prepared by taking estradiol and progesterone. She got pregnant and gave birth nine months later to a baby boy.
This is the first successful pregnancy in a cancer survivor following IVM and egg freezing, according to the report. "IVM enables us to freeze eggs or embryos in urgent situations or when it would be hazardous for the patient to undergo ovarian stimulation," Grynberg said in a press release. "In addition, using them is not associated with a risk of cancer occurrence." Grynberg says his team has vitrified "lots of eggs" in this same way for other cancer patients, and he believes this case shows it is now a viable option.
Karen Glass, a fertility doctor at CReATe Fertility Centre in Toronto, believes that traditional ovarian stimulation is still a woman's best option for fertility preservation in the face of cancer. "All of the research shows that in vitro maturation has lower success rate than traditional IVF," she says. And while she understands that the hormone drugs used in stimulation are a theoretical concern for cancer patients, she says the research so far indicates there are no long-term detrimental outcomes from the 10 or 11 days a woman is on the drugs. "There is no increased risk of metastases or anything like this in people who have done IVF for fertility preservation."
M. Grynberg et al. "First birth achieved after fertility preservation using vitrification of in vitro matured oocytes in a woman with breast cancer." Annals of Oncology. 2020.
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