Fertility drugs are used to stimulate the ovaries to produce multiple follicles. Their use is associated with multiple ovulations and often with high estrogen levels. It would therefore be reasonable to ask, “Do fertility drugs cause cancer?”
This is an important issue as there are approximately one million IVF cycles reported per year worldwide. In addition, there are an unknown number of ovulation induction cycles.
For Many Women with Fertility Issues, Cancer Risks are Already Higher
Studying this issue is complicated by the fact that women with different diagnoses end up using the same fertility drugs. These include problems at the level of the brain (hypothalamic amenorrhea), polycystic ovary syndrome (PCOS), male infertility, tubal factor infertility, endometriosis and unexplained infertility.
Of these, certain subgroups-- patients who have never been pregnant (nulliparity), patients with endometriosis, and those that do not ovulate (anovulation)-- are independently associated with an increased cancer risk. Studies that include an increased number of these subgroups could lead to bias in the conclusion.
Evaluating the Evidence for Signs of a Link to Fertility Drugs
The Practice Committee of the American Society for Reproductive Medicine (ASRM) recently published its guidelines on this issue. They assessed a total of 1,332 studies identified in an electronic search, and included 113 studies that met their eligibility criteria. Here is a summary of their conclusions:
Several studies had methodological issues including small sample sizes, varied treatment regimens, inadequate information about duration and dose of treatment, retrospective analyses, and short follow-up periods.
Overall, there is fair evidence that women with infertility have an increased risk of breast, ovarian, and endometrial cancer.
Based on available data, we can be reasonably reassured that there is no meaningful increased risk of invasive ovarian cancer following the use of fertility drugs in infertile women.
Based on the available data, there is fair evidence that the risk of invasive ovarian cancer is not different with one fertility drug compared with another.
There is fair evidence that fertility drugs are not associated with an increased risk of breast, uterine, cervical, thyroid, colon cancer. There is insufficient evidence that fertility drugs are associated with melanoma and lymphoma.
What Does All This Mean?
Infertile women might be at an increased risk of invasive ovarian, uterine (endometrial), and breast cancer. However, use of fertility drugs does not appear to increase this risk.
Questions about Fertility Drugs and Cancer Risk?
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Dr. Karande is Board Certified in the specialty of Obstetrics and Gynecology as well as the subspecialty of Reproductive Endocrinology and Infertility. He is a Fellow of the American College of Obstetricians and Gynecologists and Member of the American Society for Reproductive Medicine.