By Alanna Kennedy
Focus on Fertility
Ongoing research aims to expand options for preserving fertility before and after cancer treatment
By Alanna Kennedy
OPTIONS BEFORE TREATMENT
The best time for cancer patients to preserve their fertility is before treatment starts, when there are several options for men and women who think they may want to have biological children after cancer.
For women, the most common procedure is embryo freezing, which has been available for more than 25 years. The first step in the process is a regimen of shots that stimulate the ovaries to mature multiple eggs at once. This is followed by a medication that induces ovulation, after which the eggs are removed with a needle by a physician. The doctor then uses sperm to fertilize the eggs in a lab. When the eggs develop into embryos, they’re frozen.
While thousands of women have had successful pregnancies after using this method, there are drawbacks to it. Some women can’t delay cancer treatment long enough to complete the process, which takes at least two weeks. And the hormones necessary to stimulate egg production and ovulation might not be safe for some women who have estrogen receptor–positive breast cancer.
Beyond these challenges, not all women who are diagnosed have a partner. Using donor sperm is one solution, but many women don’t want to do that, says Melissa Sileo, a social worker who manages LiveStrong’s SurvivorCare program. For these women, egg freezing is an alternative.
With egg freezing, the egg collection process is the same as the one used by women who are freezing embryos, so time constraints and hormonal injections are still an obstacle for some cancer patients. In this case, though, the eggs can be kept frozen until the woman is ready to have a child. Once thawed, the eggs are artificially fertilized with sperm from the woman’s partner or a donor, and one or more of the resulting embryos are implanted in the woman’s uterus. The first baby conceived from a frozen egg was born in 1986; more than 900 babies have been born this way since. Nonetheless, according to Levine, doctors still consider the technique to be experimental.
For women whose tight treatment timelines don’t allow for egg harvesting, ovarian tissue cryopreservation may be an option. This method involves surgically removing part or all of an ovary and freezing it. After cancer therapy is completed, surgeons return the frozen tissue to the woman’s body.
Ovarian tissue cryopreservation is a new technology, and doctors can’t be entirely sure how effective it is yet. Fewer than 20 women have undergone the procedure, become pregnant and given birth—the first in 2004—and doctors don’t know for certain whether these women ovulated from the replaced tissue or from an ovary that wasn’t removed, says Levine.
The risks of ovarian tissue freezing are also still unknown. Researchers in Belgium recently reported that the tissue can potentially harbor malignant cells, and they suggest that its re-implantation may put survivors at risk of recurrence. In a small study published online July 1 in the journal Blood, the scientists reported molecular evidence of cancer in frozen ovarian tissue from seven out of 10 patients with acute lymphoblastic leukemia (ALL) and two out of six patients with chronic myelogenous leukemia (CML). Going a step further, the researchers found that four out of 12 mice implanted with the ALL patients’ ovarian tissue developed tumors, although none of the six mice they implanted with CML patients’ tissue developed tumors.