Breast cancer illustration showing one breast with cancerous tissue fluorescing
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Young women with breast cancer are not at increased risk for disease recurrence or death if they choose to undergo fertility preservation procedures prior to treatment, report researchers from the Karolinska Institutet in Stockholm, Sweden.

The reassuring findings “add to the growing evidence on safety of fertility preservation in young women with breast cancer,” said lead researcher Kenny Rodriguez-Wallberg, adjunct professor and research group leader at the Department of Oncology-Pathology, Karolinska Institutet, and chief physician at Karolinska University Hospital. “Having a chance to build a family after being cured is an issue of great importance for young people with cancer, with a potential to improve their future quality of life.”

Speaking to Inside Precision Medicine, Rodriguez-Wallberg explained that “breast cancer is the most common cancer in women of reproductive age, and it is the most common indication for fertility preservation in women in Sweden and in many other countries.”

Fertility preservation is achieved through cryopreservation—the freezing of ovarian tissue, embryos, or oocytes. The latter two methods require the woman to undergo approximately 2 weeks of controlled ovarian stimulation, which results in elevated levels of estradiol. In theory, this could stimulate the growth of hormone-sensitive breast cancer and increase the risk of it spreading, but Rodriguez-Wallberg notes that so far, no studies have found any increased risks of breast cancer relapse or mortality in women undergoing fertility preservation.

In spite of this “it is not unusual that women with hormone-positive breast cancer or their treating doctors opt out of the procedures for fertility preservation because of the fear that these procedures will increase the risk of cancer recurrence or death,” said the study’s first author Anna Marklund, researcher at the Department of Oncology-Pathology, Karolinska Institutet.

To address these fears, Rodriguez-Wallberg and team reviewed data for 1,275 women of childbearing age who were treated for breast cancer in Sweden between 1994 and 2017. Of these, 425 underwent procedures for fertility preservation with (n=367) or without (n=58) hormonal stimulation, and 850, matched for age, time of diagnosis, and region, did not.

The researchers report in JAMA Oncology that, after adjustment for potentially confounding factors, there were no significant differences in breast cancer-specific mortality and breast cancer recurrence rates between the women who did and did not undergo fertility preservation.

At 5-years after breast cancer treatment, 96% of women who underwent hormonal fertility preservation, 93% of those who received nonhormonal fertility preservation, and 90% of women who did not undergo fertility preservation were still alive.

The corresponding proportions of women who were alive and had not experienced breast cancer recurrence within 5 years were 89%, 83%, and 82%, in a subgroup of 723 women who had sufficient data to analyze this outcome.

Rodriguez-Wallberg et al. point out that the risk for breast cancer recurrence was slightly lower, but not significantly so, in the women who underwent hormonal fertility preservation than in those who had no fertility preservation and suggest that this tendency might be a result of a “healthy [fertility preservation] effect.” Rodriguez-Wallberg said this means that “women who feel healthier and appreciate their prognosis to be good are probably more prone to opt for fertility preservation at the time of breast cancer diagnosis.”

He added that the team plans to investigate this phenomenon further during an additional 5 years of follow-up.

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