Risk of Infertility in Reproductive-Age Patients With Thyroid Cancer Receiving or Not Receiving 131I Treatment

Background Fertility is the crucial concern for many survivors of cancer diagnosed as children, adolescents, and young adults. The objective of this study was to determine the risk of infertility in reproductive-age patients with thyroid cancer receiving or not receiving radioiodine treatment in Taiwan. Methods This nationwide population-based cohort study was conducted using data obtained from the Taiwan National Health Insurance Database from 2009 to 2019. A total of 20,259 thyroid cancer patients aged from 15 to 50 years (8037 did not receive 131 I treatment, and 12,222 received 131 I treatment) and 20,259 controls were enrolled. A Cox proportional hazards model was applied to estimate the risk of infertility in thyroid cancer patients receiving or not receiving 131 I treatment in terms of hazard ratios and 95% confidence intervals. Results The incidence rates of infertility in thyroid cancer receiving 131 I therapy, those not receiving 131 I therapy, and controls were 5.55, 5.07, and 3.61 per 1000 person-years, respectively. Compared with thyroid cancer patients treated with a cumulative 131 I dose of 4.44 GBq or less, the risk of infertility was not significantly increased in those treated with a cumulative 131 I dose of more than 4.44 GBq (adjusted hazard ratio, 1.13; 95% confidence interval, 0.95–1.36). Conclusions The greatest increased risk of infertility in reproductive-age patients with thyroid cancer is associated with the fact that the patient has thyroid cancer regardless of 131 I administration. 131 I treatment or cumulative dose of 131 I greater than 4.44 GBq did not further increase the risk of infertility.