Use of Fertility Drugs Not Associated With Increased Breast Cancer Risk

Women with no previous history of breast cancer who underwent ovarian stimulation, via use of Clomid (clomiphene citrate) and gonadotropins, did not have an increased risk of breast cancer than those who did not undergo such treatments, according to recent research.

“(Fertility drugs are) quite hormone heavy, and with the premise of fertility treatment, the first half of it is very much focused on ovarian stimulation,” said study author Dr. Yusuf Beebeejaun, clinical research fellow in reproductive medicine at King’s College London, in an interview with CURE®. “And for that we give injections or medication that promote the hormone production within the body itself. And one of the hormones that's commonly used is (the) follicle-stimulating hormone that acts on the ovary and gets the ovary to produce as many eggs as possible.”

The concern for breast cancer in association with fertility treatments may be related to the fact that breast tissue is sensitive to estrogen action.

“To put things in perspective, one cycle of IVF (in vitro fertilization) treatment, for example, can equate to one to two years of menstrual cycles condensed in that period of time,” Beebeejaun explained. “So while your body could produce estrogen at that level, when you have an IVF it goes exponentially high. And it's that sudden rise and exponential action of estrogen on the breast that brought up this research study about whether the use of IVF treatment – because there are different forms of IVF, different forms of this treatment – whether their usage of all this combination of drugs, alone and combined, has an effect of breast tissue and the risk of having breast cancer.”

To discount this uncertainty, research was conducted by investigators from King’s College London in partnership with King’s Fertility and was published in Fertility and Sterility.

The researchers analyzed electronic databases from 1990 to January 2020 involving 1.8 million women from around the world who underwent fertility treatments and were seen in follow-ups for an average of 27 years.

“That's important because women of reproductive age come between the age of (about) 21 to 35, for example,” said Beebeejaun.

The researchers included all cohort studies reporting new incidences of breast cancer in women using ovarian-stimulating drugs. The treated women with infertility were then compared with the untreated general population of women with infertility. This meta-analysis was the largest study to date assessing cancer risk of fertility drugs.

The study authors found no significant increase in risk for breast cancer in women who received the treatments as opposed to untreated women.

“You may be aware of conditions like polycystic ovaries (PCOS), for example,” Beebeejaun explained. “So that's a common cause of infertility itself. Or you may have people who need fertility treatment such as IVF, the medication and treatment for each of these conditions are not the same, but the way the hormonal response is within body is about the same.”

He added that the results give women receiving fertility treatments the extra level of reassurance they need that there will be no increased risk of breast cancer.

“There's enough to worry about the fertility point of view, because it is an emotional journey,” Beebeejaun said. “I see that through a lot of the patients that I see coming in here for fertility treatment, but you need to appreciate that it’s not an easy route to take. And it is emotionally taxing and time consuming. It requires a lot of scans, a lot of monitoring, etc. Having that level of reassurance that that treatment is safe, it’s not putting me or any of the cells that can be more sensitive at increased risk of having cancer in the long term is what’s required.”

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