Is the risk of developing thyroid cancer higher in women with infertility?


This study examined if infertility was associated with a higher risk of developing thyroid cancer in women.

This study concluded that women with infertility have a higher risk of developing thyroid cancer when compared to fertile women.

Infertility in women is a problem worldwide. These patients are often treated with hormones. Thyroid cancer is a condition that appears more commonly in women than in men. This could be related to the presence of female hormones. The thyroid gland is normally more active in pregnant or breastfeeding women. This has been found to be associated with thyroid cancer in prior studies. However, the risk of developing thyroid cancer in women with infertility, or taking infertility medications is still unclear. 

For this study, 13,356 women with infertility were compared to 53,424 fertile women. This study collected information from insurance records. Patients were followed up for an average of 7 years. The risk of developing thyroid cancer was recorded. 

The number of patients with infertility who developed thyroid cancer was 1.9 times higher than that of fertile patients. In women with infertility, thyroid cancer was more commonly diagnosed after seven years of follow up.

When infertility drugs the patients were taking were evaluated, women treated with clomiphene (Clomid) had a lower risk of developing thyroid cancer than those not taking the drug. However, women who took clomiphene were 6 times more likely to develop thyroid cancer compared to fertile women. In women with infertility, thyroid cancer was 3 times more common if they took estrogen. This risk was 4 times more common if they took progesterone. 

The authors concluded that women with infertility have a higher risk of developing thyroid cancer when compared to fertile women.

This study looked at patients over a relatively short period of time. We do not know the long term risk of developing thyroid cancer in this group. Also, the study was based in Taiwan. These results may not apply to all women.

If you have any concerns regarding fertility treatment or thyroid cancer risk, please discuss this with your doctor.