Fertility drugs may slightly increase the risk of certain cancers—including ovarian and endometrial cancer, especially with extended use or high doses, but do not appear to raise breast cancer risk for most women, according to recent large studies.
Ovarian and Endometrial Cancer Risks
- Clomiphene citrate (Clomid): Multiple studies report a modest increase in endometrial cancer risk in women exposed to high cumulative doses or a large number of cycles (such as >2,000 mg or >7 cycles). This risk is partly attributed to underlying causes of infertility (like PCOS or anovulation), obesity, and not just the drug itself.
- Gonadotropins (FSH, hMG, hCG): Evidence on increased risk for ovarian and endometrial cancer is inconclusive, but some data suggest risk rises when combined with Clomiphene, or with prolonged exposure.
- Ovarian cancer: Fertility medications modestly increase ovarian cancer odds, especially after multiple treatment cycles or for women with persistent infertility, but most women who take fertility drugs do not develop cancer.
Breast Cancer Risk
- Large, long-term cohort studies and meta-analyses show no significant increase in breast cancer risk after fertility treatments, including IVF and use of Clomiphene, hormone injections, or progesterone, regardless of number of cycles or drugs used.
- This finding holds for women with BRCA mutations, younger and older age at treatment, and in comparison to infertile women not using fertility drugs.
Other Considerations
- Fertility drugs can transiently raise estrogen and progesterone levels, stimulating some tissues’ growth—but so far, research shows no strong, lasting cancer association except potential risks mentioned above.
- Underlying infertility itself is a risk factor for gynecologic cancers, complicating interpretation of study results.
In summary, fertility drugs may moderately increase the risk of ovarian and endometrial cancer, especially with repeated, high-dose usage, but do not seem to elevate breast cancer risk. Risk should be balanced against the benefits of treatment and discussed with a reproductive endocrinologist.
