Do Fertility Drugs Increase Your Risk of Breast Cancer?

PJ Hamel Health Guide
  • Millions of American women take fertility drugs to help them conceive and bear children. A new study examines whether the use of these drugs increase a woman’s risk of breast cancer later in life.

    When you’re a younger woman longing for a child, and unable to conceive, fears of being diagnosed with breast cancer later in life take a back seat to having a baby – before it’s too late.

    With the biological clock ticking, the imperative to become a mother outweighs all other health issues. Breast cancer risk is a classic case of “We’ll cross that bridge when we come to it.”

    A new study from the National Institutes of Health, published July 6 in the Journal of the National Cancer Institute, clarifies earlier studies looking at possible links between fertility drugs and breast cancer.

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    Let’s step back a minute. Scientists have long believed that fertility drugs may be connected, in some way, to breast cancer risk.

    After all, these drugs influence the levels of hormones that are key players in 80% of breast cancer diagnoses. It would make sense that fertility drug use might either increase or reduce your risk of breast cancer.

    According to this newest NIH study, it does both.

    The NIH’s Two Sister Study involved over 1,400 women, comparing those who’d been diagnosed with breast cancer under age 50 (“young-onset breast cancer”) with their cancer-free biological sisters.

    Women in the group who’d taken fertility drugs – clomiphene citrate (CC); or CC plus follicle stimulating hormone (FSH) – and hadn’t become pregnant showed a reduced risk of young-onset breast cancer.

    Why this reduced risk? Researchers don’t know, but do have a theory. CC is a SERM (selective estrogen receptor modulator), and SERMs have been proven to lower the risk of breast cancer. Thus, fertility drugs may help prevent breast cancer. (Breast cancer survivors commonly take another SERM, tamoxifen, to reduce their risk of recurrence.)   

    On the other hand, women taking CC (or CC and FSH) who did become pregnant, or carried a baby for at least 10 weeks, saw their risk of young-onset breast cancer increase, compared to those whose treatment didn’t result in pregnancy.

    Thankfully, that increased risk was no greater than that of their sisters, or of the general population – women who’d never taken fertility drugs.

    Dr. Louise Brinton, PhD, Chief of Hormonal and Reproductive Epidemiology at the National Cancer Institute, suggests that women who successfully take fertility drugs and become pregnant see their risk of breast cancer rise temporarily, but that the risk “dissipates with time and eventually leads to a long-term risk reduction.” (Pal, 2012)

    This makes sense; it’s long been know that women who have children, whether or not they’ve taken fertility drugs, are less likely to be diagnosed with breast cancer.

    Bottom line: if you want children and have trouble becoming pregnant, a fear of breast cancer later in life shouldn’t prevent you from taking fertility drugs.

  • The temporary increase in breast cancer risk is far outweighed by childbearing’s long-term benefits: chief of which is that child you’ve been longing to have.

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    Pal, S. (2012, July 6). Fertility tx may alter cancer risk. Retrieved from 

    Gann, C. (2012, July 6). Fertility drugs' link to breast cancer hinges on pregnancy, study says. Retrieved from

Published On: September 19, 2012