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Breast Cancer and Fertility Drugs

a blog by Julie Monacelli, October 11, 2013

When we began fertility treatments, I looked into the risks of cancer involved with the medications I would take. I have to admit, I must have done some pretty incomplete research since my reading for this blog stopped me dead in my tracks. As I read the Two Sisters study, which was done from 2008-2010 and involved over 1422 women who had been diagnosed with breast cancer and their 1669 sisters who hadn’t. They found that women who used fertility medications, specifically Clomid, and did successfully conceive had an increased incidence of breast cancer. Women who took the medications, and did not carry a pregnancy beyond 10 weeks had a lower risk. Wait, what?

The study had some significant limitations: First, breast cancer risk increases with age. This study was done on younger women, and their risk for breast cancer is usually linked to the breast cancer gene. It isn’t noted if any of these women had either of the genes, which would be a significant finding. BRCA1 and BRCA2 are the names of the two breast cancer genes. Second, the women all self-reported their fertility medication use. Accuracy was not verified.

In the end, it is believed the women who took the fertility medication and did not conceive had no increased protection from breast cancer because of their fertility treatments. Instead, it is thought those women had naturally lower estrogen levels. Estrogen feeds breast cancer cells, which would mean infertile women may have a decreased incidence of breast cancer.

Infertility may provide an unexpected benefit after all.

To read more about fertility and breast cancer, check out these articles on

Fertility and Breast Cancer

Link Between IVF in Young Women and Breast Cancer

FertilityAuthority's Five Questions to Ask about Your Fertility after a Breast Cancer Diagnosis

Life after Cancer and Preserving Fertility for the Future


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