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Janet Gray, Ph.D.
Janet Gray, Ph.D.

As author of our 2008 and 2010 State of the Evidence reports, Dr. Gray drives the science behind all our work.

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Infertility Treatment Drugs

FOUND IN: Medication

THE GIST: At the moment, no clear link has been established between infertility drugs and breast cancer risk. Additional research is needed to investigate this further. A recent study did show an increase in breast cancer risk for women who started infertility drug treatments before the age of 24, and a link has been found for women treated with high doses of the drug clomiphene citrate.

State of the Evidence on Infertility Treatment Drugs

Despite the substantial evidence linking hormone replacement therapy (HRT) and oral contraceptive use with increased incidence of breast cancer, neither the condition of subfertility nor the use of infertility-treatment (ovulation-stimulation) drugs appears to have a clear link to the disease (Gauthier, 2004; Klipp, 2000; Orgeas, 2009). This is true also when the study involves infertile women who are BRCA carriers (Kotsopoulos, 2008). Where the link has been found, it has been for women who have been treated with high doses of the fertility drug clomiphene citrate.

TIPS FOR PREVENTION

Do your research before starting infertility treatments and be cognizant of the risk factors associated with clomiphene citrate.

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Two studies found increased risk of breast cancer for women who have been treated for ovarian infertility with drugs including gonadotropins or clomiphene citrate. However, the results were statistically significant only when the incidence of breast cancer was compared with the incidence in the general population of women, but not with the more appropriate control of women with ovarian infertility who have not been treated with fertility drugs (Brinton, 2004: dos Santos Silva, 2009). Two other studies, however, have found small but statistically significant increases in breast cancer rates in women taking clomiphene citrate compared with rates for infertile women taking no infertility treatment (Calderon-Margalit, 2009; Lerner-Geva, 2006). Looking at a smaller subgroup of women whose infertility was not ovarian in origin and who underwent multiple treatments with high doses of clomiphene citrate, research showed this group to have substantially increased risk of later developing breast cancer (Orgeas, 2009).

A very recent study complicates the story, however. Within the group of women with fertility problems, there was no difference in the rate of breast cancer when general comparisons were made between women who had taken fertility drugs and those who had not. But when age at treatment was factored in, a statistically significant increase in breast cancer risk was found in women who had begun infertility drug treatments before the age of 24, as compared with infertile women of the same age who had not undergone in vitro fertilization (IVF) and associated drug treatments. Increased risks for breast cancer were not associated with infertility treatment in older women (after age 40) who underwent IVF protocols (Stewart, 2012).

*For chemicals that have been shown to be carcinogens, we provide classifications from two authoritative bodies: the International Agency for Research on Cancer (IARC, an international body) and the National Toxicology Program (NTP, a division of the U.S. Department of Health and Human Services). We have categorized endocrine-disrupting compounds where the body of peer-reviewed research indicates a strong foundation for doing so.