Do Fertility Treatments Increase the Risk of Breast Cancer?

The results of a recently released meta-analysis found no links between fertility treatments and breast cancer. These findings were published online in the medical journal Fertility and Sterility on June 21, 2021. 

A meta-analysis is a type of study that combines and analyzes the results of various earlier studies. In this case, the researchers reviewed 20 studies focused on whether drugs that stimulate the ovaries to release eggs also increased the risk of breast cancer. The patients studied were women with no previous history of breast cancer who used medicine to stimulate their ovaries. Though ovarian stimulation drugs have been used to treat infertility since the early 1960s, the study focused on women who used them between 1990 and January 2020. 

Since fertility drugs greatly increase the amount of estrogen in the body, this could theoretically stimulate the growth of certain breast cancer cells as well, which is why the issue has been studied for decades. 

Though the results of this meta-analysis are encouraging, it is not the final word on the subject. Researchers noted that the quality of the evidence was low because many of the studies they reviewed were not randomized, so the results could have been biased. Also, results from earlier studies on possible links between fertility drugs and breast cancer risk have been mixed, so researchers haven’t yet been able to make a conclusive connection. Still, this study does introduce a useful body of evidence to consider.  

How Fertility Drugs Work

Ovarian stimulation drugs cause the ovaries to develop and release eggs. This mimics what the hormone estrogen does in the body, except that fertility drugs stimulate the ovaries to produce more mature eggs than normal. With fertility drugs, many mature eggs can be released in a single cycle. Without them, only one, and sometimes two, eggs per cycle are released. 

There are two primary drugs used to stimulate the ovaries: clomiphene citrate and gonadotropins. Clomiphene citrate is taken orally once a day for five days, starting on day five of a woman’s menstrual cycle. Gonadotropins refer to three types of hormones that regulate ovarian and testicular function. These are usually administered by injection. Doctors sometimes combine clomiphene citrate and gonadotropins for certain procedures, including in vitro fertilization. 

If you have concerns or questions about any fertility medications and the impact on your breast health, reach out to your healthcare team about risk factors. When you are ready to get started to find your perfect donor, contact our Client Services team for help on every step of your journey to parenthood. Call us at (206) 588-1484 or reach us via email

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