Fertility Preservation Safe for Young Women with Breast Cancer

December 22, 2020, by NCI Staff

Common methods of preserving a woman’s fertility before starting breast cancer treatment are safe for young women, according to a large study that tracked Swedish women for more than 2 decades.

About 6% of the women who chose to freeze their embryos, eggs, or ovarian tissue before undergoing treatment for breast cancer died over the 23 years covered by the study. During the same period, 13% of matched women who didn’t undergo fertility preservation died, according to the study results published on November 19 in JAMA Oncology.

For several reasons, such as age and breast cancer risk, direct comparisons between these two groups are difficult to make, explained Emily Tonorezos, M.D., director of NCI’s Office of Cancer Survivorship.

“But at the same time, this is very reassuring evidence about survival” after fertility preservation and childbirth, Dr. Tonorezos said.

Only 9 out of 425 women in the study who underwent fertility preservation—about 2%—later used their banked embryos, eggs, or ovarian tissue.

But, given the large number of women diagnosed with breast cancer every year, “that’s clinically meaningful, especially as there’s no downside in terms of survival,” said Jennifer Levine, M.D., who specializes in fertility after cancer treatment at Weill Cornell Medicine and New York-Presbyterian and was not involved in the current study.

“In my mind, that makes the case that these procedures should be considered a standard part of treatment for those who want it,” she said.

Residual Concerns about Risk

Studies have found that about half of young women with breast cancer say they would like to have a child after completing treatment. But some treatments for breast cancer, such as certain types of chemotherapy, can cause infertility.

Fertility preservation after a breast cancer diagnosis can be complicated. While men can bank sperm quickly, collecting eggs from a woman and potentially creating fertilized embryos for storage (via cryopreservation) requires delaying some parts of cancer treatment for weeks or months.

In addition, methods used for preserving fertility at diagnosis—and then later in assisted reproductive technology (including in vitro fertilization, or IVF) to conceive—involve the use of hormones that cause estrogen levels to rise. Historically, health care providers had concerns that these procedures could pose a risk for women with breast cancer, especially those with hormone receptor–positive tumors.

Many women also take drugs to block hormones for up to 5 years after surgery for breast cancer. If they want to get pregnant during that time, a treatment interruption is required, explained Ann Partridge, M.D., who leads a clinic for young breast cancer survivors at Dana-Farber Cancer Institute and was not involved in the study. And pregnancy itself produces a bevy of hormones for 9 months that could potentially fuel the growth of breast cancer cells, she added.

“Twenty years ago, everybody was afraid that undergoing fertility preservation, or conceiving after breast cancer, was going to add fuel to the fire,” said Dr. Partridge. Although those concerns have largely been put to rest, “it’s reassuring that there was no apparent harm in having a pregnancy or using assisted reproductive technology after breast cancer for these women,” she said.

Successful Births after Cancer Treatment

In the new study, researchers from Karolinska University in Sweden followed 425 women with breast cancer, aged 21 to 42 at diagnosis, who underwent fertility preservation between 1994 and 2017.

For each of those women, the researchers identified two other women with breast cancer who did not undergo fertility preservation for comparison. Women were matched by age at diagnosis, year of diagnosis, and where they lived.

Overall, 97 women in the fertility preservation group later gave birth to at least one child. Of those women, 20 used some form of assisted reproductive technology to conceive, and of those, 9 used embryos, eggs, or ovarian tissue banked before cancer treatment.

Among the 850 women who didn’t undergo fertility preservation, 74 eventually gave birth to at least one child. Three of those women used assisted reproductive technology to conceive.

Although a greater percentage of women in the fertility preservation group (23% versus 9%) eventually had a successful pregnancy, the researchers couldn’t directly compare the groups because it was unclear how many women in each group wanted to get pregnant, said Dr. Partridge. Women who had chosen fertility preservation were likely more motivated to have a baby, she explained.

“You can’t really conclude from this [study] that women who undergo fertility preservation are more likely to get pregnant than the women who don't, independent of a desire to have a baby,” she said.

The women in the two groups also can’t be directly compared in terms of survival because of inherent differences, explained Dr. Partridge. For example, those who underwent fertility preservation were likely healthier and at lower risk of cancer recurrence, a phenomenon called the healthy mother effect.

Many Unanswered Questions

In the United States, large barriers remain for women with cancer who want to preserve their fertility, explained Dr. Levine. For instance, while fertility preservation is available to all women in Sweden under their national health system, many insurance plans in the United States don’t cover it for young cancer patients.

“States are starting to issue mandates related to health insurance coverage of fertility preservation,” Dr. Levine said. “Nine states now have mandates: some of them are specific to cancer.” However, this still leaves many women forced to pay out of pocket for fertility services, where bills can easily run over $15,000, she explained.

“I would argue that this [study] supports the idea that everybody should have the option to be covered by insurance to pursue fertility preservation,” added Dr. Levine.

“In some ways this is a gender equity issue, because, for men, banking sperm is much less expensive,” said Dr. Tonorezos. Both the collection procedure and long-term storage are less costly for men, she explained.

On the flip side, explained Dr. Partridge, more research is needed to determine which young women with breast cancer are most likely to need fertility preservation. Many younger women won’t have their fertility impacted by cancer therapy, but currently it’s not possible to predict that ahead of time, she said, leading many to undergo unnecessary fertility treatments.

And more studies need to look at the success rate for pregnancy after fertility preservation for these women, added Dr. Levine. “We’re limited, when we counsel patients, by not having that information,” she said.

“There’s a lot that goes into these decisions around the time of diagnosis,” agreed Dr. Tonorezos. "What opportunities are available to a woman medically, how she thinks about herself and her future childbearing potential—those things are so important for helping people understand risk and benefit when making their decisions about fertility preservation."