Interview Isabelle Demeestere: Impact of breast cancer on fertility

"Having a child is still possible."

In the past, young women who had gone through breast cancer were given the cautious advice to shelve the desire for children for good. Pregnancy might increase the chances of relapse, it was suspected. After all, pregnancy turns your hormone balance upside down, something you can do without if you have been treated for a - usually - hormone-sensitive tumor, the reasoning went. That idea is still alive and well here and there, but is totally outdated. "Today we know that pregnancy after breast cancer does not increase the risk of relapse at all, for any type of breast cancer, hormone-sensitive or not," assures Professor Isabelle Demeestere, gynecologist at the Erasmus Hospital in Brussels and scientific researcher at the FNRS. Demeestere specializes in cancer and fertility. "There are now enough large studies that confirm this. Women can conceive with confidence even after breast cancer."

"Six to 8 percent of all women diagnosed with breast cancer are under the age of 40. This is not small, given that breast cancer is common," Isabelle Demeestere continued. "In Belgium, it is estimated that about 500 women are affected each year in their reproductive years." Maintaining fertility is a top priority for them. Yet an unfulfilled desire for children is often the last thing on these women's minds when faced with a breast cancer diagnosis. First and foremost, they want to survive the cancer. "The treating physician has to take the initiative. It is incredibly important to discuss the desire to have children before starting treatment for breast cancer," sounds determined.

Chemotherapy

Breast cancer does not affect fertility, neither does surgery and radiation to the breast region. It is the drug treatments, especially chemotherapy, that have a bad reputation in that area. "Because breast cancer is not systematically detected in young women, they are more likely to have a slightly more advanced breast cancer at the time of diagnosis," Professor Demeestere explains. "For this reason, chemotherapy is used more often in them, and chemotherapy can interfere with the function of the ovaries." Not all breast cancer patients who receive chemo become infertile as a result, but the chances would be reduced by 30 to 60%.

Isabelle Demeestere does not like to express the chances of pregnancy in numbers. "Very young women have a real chance of spontaneous ovarian tissue recovery. They tolerate the medication better or just have enough eggs in the ovaries," she echoes. "After chemotherapy, it can take as much as six months to a year for the menstrual cycle to start up again, and even after that, fertility problems can arise."

Eggs in the freezer

There are several possible solutions for women with breast cancer and a desire to have children who must receive chemotherapy. "The most obvious choice is to remove eggs to freeze them for later," Demeestere reassures. To harvest as many mature eggs as possible, the ovaries must first be hormonally stimulated, with daily hormone injections for 10 to 14 days. "The hormones administered to stimulate the ovaries are combined with another drug, which keeps the cancer from growing," the gynecologist points out. "Because the egg pick-up has to happen even before breast cancer treatment starts." Most breast cancers are hormone-sensitive, and with hormones you always have to be careful not to make the cancer worse. "Women who choose stimulation and egg retrieval are remarkably positive about it," Demeestere says. "It gives them perspective for their life after breast cancer. It also inspires confidence when doctors put effort into it."

In order not to delay breast cancer treatment for too long, the women undergo only 1 stimulation cycle. "We cannot guarantee that the frozen eggs will fulfill their desire for children after breast cancer. It depends on age and the number of eggs harvested. On average, a woman younger than 36 whose eggs we can freeze 8 to 10 has a 40-50% chance of pregnancy after cancer treatment." Certainly not bad, but not super good either. If the woman has a partner, one can also opt for in vitro fertilization, after which embryos are frozen. The chances of pregnancy are better.

"It is incredibly important to discuss the desire to have children before starting treatment for breast cancer." - Expert Isabelle Demeestere, gynecologist at the Erasmus Hospital in Brussels and scientific researcher at the FNRS

Ovarian tissue

There are also drugs that reduce the toxic effects of chemotherapy, reducing the risk of ovarian damage. "Those drugs can be used with chemotherapy for hormone-sensitive breast cancers to reduce the risk of relapse," says Demeestere. "We start it toward the end of chemotherapy in women who still have a desire to have children." It is not a true alternative to freezing, but sometimes an additional one. "Another option is to remove ovarian tissue through minor surgery and freeze that tissue. In that case, you don't have to undergo hormonal stimulation and egg retrieval. So it's faster." Ovarian tissue also contains egg cells, but they are immature and therefore not useful for in vitro fertilization, like the eggs obtained after stimulation. "We re-implant the removed tissue on the remaining ovarian tissue once the treatment is over, and hope that the procedure will help the ovaries regain their function. Unfortunately, the chances of pregnancy are low. Therefore, we only suggest the technique to women under 30 who do not wish to delay their breast cancer treatment, do not wish stimulation, or in whom it is indeed best to start treatment as soon as possible." Sometimes both techniques - egg freezing and ovarian tissue sampling - are combined to optimize the chances.

Sensitize

Doctors dealing with young breast cancer patients should bring up the desire to have children, whether there is a partner or not. "We take every opportunity to sensitize people about it," smiles Demeestere. "Belgium is one of the first countries to have a fertility preservation program for young women undergoing cancer treatment. Many foreign patients come to our hospitals for this. We are strong in this field and we want all young women with breast cancer to be able to take advantage of it."

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