For many struggling with infertility, fertility medications offer hope. But with the rise of assisted reproductive technologies (ART) like in vitro fertilization (IVF) and ovulation-inducing drugs, concerns have emerged about long-term risks—especially fertility drugs and cancer risk.

So, do fertility drugs actually cause cancer? Current research does not provide conclusive evidence that fertility medications directly cause cancer. However, some studies suggest a possible link between certain fertility treatments and a higher risk of ovarian and thyroid cancers, while others show no significant connection. Let’s break down the key findings.

Understanding the Concern: How Fertility Drugs Affect the Body

Fertility medications stimulate the ovaries to produce eggs, increasing hormones like estrogen and progesterone. Some cancers—such as breast, ovarian, and uterine cancers—are hormone-sensitive, leading researchers to question whether fertility drugs could contribute to cancer. Additionally, some women undergoing fertility treatments already have conditions like endometriosis or hormonal imbalances, which can increase cancer risk. This makes it hard to determine if fertility drugs are the cause or if other factors are involved.

What the Research Says About Fertility Drugs and Cancer Risk

Breast Cancer

Many women worry that fertility drugs might increase breast cancer risk due to hormone changes. However, research does not support this concern. Studies show no clear link between fertility medications and breast cancer. That said, prolonged use of clomiphene citrate (a common ovulation-inducing drug) beyond 10 cycles is discouraged due to unknown long-term effects.

Ovarian Cancer and Borderline Ovarian Tumors

Ovarian cancer is a major concern regarding fertility medications. Some studies suggest that women who use fertility drugs, especially those who remain childless after treatment, may have a slightly higher ovarian cancer risk. However, infertility itself is a known risk factor, making it unclear whether drugs or underlying fertility issues are to blame.

Some research also suggests a link between assisted reproductive technology (ART) and borderline ovarian tumors, which are abnormal but typically not invasive. Again, it’s unclear whether fertility treatments or other factors like endometriosis play a role.

Uterine (Endometrial) Cancer

There is no conclusive evidence linking fertility medications to uterine cancer. Instead, researchers believe that pre-existing infertility-related conditions, such as polycystic ovary syndrome (PCOS) and irregular ovulation, may be responsible for an increased risk.

Thyroid Cancer

Some studies suggest that high doses of clomiphene citrate over long periods may slightly increase thyroid cancer risk. However, data is limited, and the overall risk appears to be small. More research is needed.

Cancers with No Known Link to Fertility Drugs

Current research has found no increased risk of the following cancers due to fertility treatments:

• Colon Cancer
• Cervical Cancer
• Non-Hodgkin Lymphoma
• Melanoma (though data is insufficient to rule out a link entirely)

Why Is It Hard to Get a Clear Answer about Fertility Drugs and Cancer Risk?

Studying the long-term effects of fertility medications is complicated for several reasons:

1. Infertility Itself May Be a Risk Factor – Many women undergoing treatment have conditions like endometriosis or PCOS, already linked to increased cancer risk.
2. Cancer Develops Over Decades – Most reproductive cancers appear later in life, making it difficult to track long-term effects.
3. Low Cancer Incidence Rates – The overall risk of reproductive cancers is low, making it harder to establish strong links.
4. Study Limitations – Some studies have small sample sizes, lack control groups, or rely on patient recall, leading to potential bias.

What Does This Mean for Women Considering Fertility Treatment?

If you’re considering fertility medications, here’s what you need to know:

• The overall risk of cancer from fertility drugs appears to be very low.
• Infertility itself is a risk factor for some cancers, making it difficult to separate drug effects from underlying health issues.
• Prolonged use of ovulation-stimulating drugs, especially clomiphene citrate, should be monitored.
• Talk to your doctor about your medical and family history to assess risks and make informed choices.

The Bottom Line

Fertility treatments have helped millions achieve parenthood, and for most women, the benefits far outweigh any potential risks. While research continues, there is no solid evidence that fertility medications cause cancer. Women should be aware of potential risks but also reassured that current studies suggest the risk is generally no different than for women not undergoing fertility treatment.

If you have concerns, speak with your doctor about your health, lifestyle, and genetic risks. With the right information, you can make the best decision for your reproductive health and future family planning.

Resource: ASRM, Fertility drugs and cancer: a guideline