Do fertility drugs raise your risk of cancer?

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by Julie Snyder

Fertility TreatmentsAbout 1 in 10 couples have problems becoming parents. Greater numbers are turning to fertility treatment, including drugs to help conceive a baby.

All medicines, including fertility drugs, come with risks. Is it true that your risk of cancer increases if you use them?

As you're searching for an answer to that question, you may find conflicting information.

Some of the earlier studies have suggested an association, but many of the newer studies have failed to detect one. Included in this group are recent meta-analyses where data from several large studies were pooled together and then examined.

Fertility drugs may alter your cancer risk

Breast cancer

Women who undergo fertility treatments take medications to stimulate their reproductive systems by temporarily raising their estrogen levels. Estrogen is known to have a significant effect on your risk of developing breast cancer.

In the past, some research has found that infertility treatments lead to a higher breast cancer risk, other studies remained inconclusive.

Do these drugs affect a woman's risk of developing breast cancer? The July 2012 "Two Sister Study" tells us that it depends -- the risk hinges on whether they actually help a woman get pregnant.

The study included 1,422 women who had been diagnosed with breast cancer when they were younger than 50 and their 1,669 sisters who hadn't been diagnosed.

The researchers found that women who used fertility drugs to successfully conceive had the same risk as women who hadn't used them.

The women who used these drugs and didn't conceive had a significantly lower risk of breast cancer than the average woman. The researchers don't think that the drugs offered protection from breast cancer. Likely, women who have trouble conceiving have lower levels of estrogen than average, and so have a lower risk of breast cancer.

Pre-existing breast cancer: If you have a preexisting breast tumor that's fed by estrogen, fertility treatment could worsen the cancer.

Ovarian cancer

Several factors reduce your risk of ovarian cancer. A woman who has had children has a lower risk of ovarian cancer than women who have no children. The risk goes down with each pregnancy. Breastfeeding may lower the risk even further. Using oral contraceptives (also known as birth control pills or 'the pill') significantly lowers the risk of ovarian cancer if taken for longer than 5 years.

Infertility itself is associated with a higher risk. "When you compare infertile women to the general population, they have a higher incidence of ovarian cancer, but not one that is caused by IVF," says Jamie Grifo, MD, program director of the NYU Fertility Center.

"When you compare infertile women to the general population, they have a higher incidence of ovarian cancer, but not one that is caused by IVF," says Jamie Grifo, MD, program director of the NYU Fertility Center.

A large Danish study published in 2009 found no association between fertility drugs and ovarian cancer.

Another Dutch study published in 2011 found that women who did IVF had a slightly higher risk of "borderline ovarian tumors" compared with infertile women who didn't undergo the treatment. Borderline ovarian tumors are not fatal and may never become malignant, but they may require surgery.

There wasn't a significant difference in rates of invasive ovarian cancers between the groups.

Do you worry that fertility treatments may up your risk of cancer?


Medical references:
- Fei, C. et al. "Fertility Drugs and Young-Onset Breast Cancer: Results From the Two Sister Study." Journal of the National Cancer Institute, published online on July 12, 2012.
- Kurta, M. et al. "Use of fertility drugs and risk of ovarian cancer: results from a u.s.-Based case-control study." Cancer Epidemiol Biomarkers Prev. 2012 Aug;21(8):1282-92.

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