A Systematic Review Examining the Effects of Therapeutic Radioactive Iodine on Ovarian Function and Future Pregnancy in Female Thyroid Cancer Survivors

Anna M. Sawka; Deepak C. Lakra; Jane Lea; Bandar Alshehri; Richard W. Tsang; James D. Brierley; Sharon Straus; Lehana Thabane; Amiram Gafni; Shereen Ezzat; Susan R. George; David P. Goldstein

Disclosures

Clin Endocrinol. 2008;69(03):479-490. 

In This Article

Abstract and Introduction

Background: For women with differentiated thyroid carcinoma (DTC), the effect of radioactive iodine (RAI) therapy on gonadal and reproductive function is an important consideration.
Objective and Methods: We systematically reviewed controlled studies examining the gonadal and reproductive effects of RAI therapy in women and adolescents surviving DTC. We searched nine electronic databases. All abstracts and papers were independently reviewed by two reviewers.
Results: After reviewing 349 unique citations and 61 full-text papers, 16 papers including data from 3023 women or adolescents with DTC were included. All studies were observational, with no long-term randomized control trial data. The age at first RAI treatment varied from 8 to 50 years and the cumulative activities of RAI administered for treatment varied from 30 to 1099 mCi. Transient absence of menstrual periods occurred in 8-27% of women within the first year after RAI, particularly in older women. In addition, RAI-treated women experienced menopause at a slightly younger age than women not treated with RAI. In the first year after RAI therapy, several studies reported increased rates of spontaneous and induced abortions. However, RAI treatment for DTC was generally not associated with a significantly increased risk of long-term infertility, miscarriage, induced abortions, stillbirths, or offspring neonatal mortality or congenital defects.
Conclusions: In female survivors of DTC, there is little observational evidence to suggest important adverse effects of RAI treatment on gonadal function, fertility or pregnancy outcomes beyond 12 months, with the exception of a possible slightly earlier age of menopause.

Thyroid cancer is the most common endocrine malignancy, such that approximately 3400 Canadians[1] and 33 550 Americans[2] were diagnosed with this condition in the past year. Moreover, these incidence figures are continuing to rise.[1,3,4] In fact, thyroid carcinoma is the sixth most common malignancy being diagnosed in Canadian women[1] and the seventh most common malignancy being diagnosed in American women.[2] Half of individuals diagnosed with thyroid carcinoma are younger than 46 years of age.[2] Yet deaths due to thyroid carcinoma are relatively infrequent,[1,2,3] particularly in the majority of new cases, which are being diagnosed at an early stage.[3] As many women are diagnosed with differentiated thyroid cancer (DTC) during the reproductive years and most of them are expected to live a normal lifespan, the effects of treatments such as radioactive iodine (RAI) on future gonadal and reproductive health are important considerations.

Our objective was to systematically review the medical literature for studies examining the gonadal and reproductive effects of RAI therapy in women with DTC. Outcomes of interest were: laboratory changes (related to pituitary hormones or sex steroids), menstrual changes, ovarian failure, fertility, and pregnancy outcomes. We have recently completed a similar review on the potential gonadal and reproductive effects of RAI treatment in male thyroid cancer survivors.[5]

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