Effects of radioiodine therapy on pregnancy and its complication in differentiated thyroid cancer comparing with their healthy sisters

Differentiated thyroid cancer (DTC) frequently occurs in women at fertility age. One of the cornerstones in treating this malignancy is Radioactive Iodine (RAI) therapy following thyroid resection. In this study, we evaluated the effect of RAI therapy on the fertility rate and pregnancy complications.

This is a retrospective study on 41 patients with differentiated thyroid cancer, with at least one experience of pregnancy after standard treatment (thyroid resection followed by radioiodine therapy). All patients have been signed a written consent form in initial admission to our department. Furthermore, we asked our patients to fill in a questionnaire about their thyroid cancer and its treatment as well as pregnancy and its complication. As a control group with no different mean age, the same checklist has also been filled in for the patient’s healthy sister too, just related to gravidity and its complications. The complications of pregnancy were registered in these patients and compared with the control group consisted of their healthy sisters. Also, the association of abortion rate with other underlying factors has been assessed. All data has been included in SPSS software, version 22 (IBM SPSS, Armonk, NY, USA) and analyzed using logistic regression. This study conducted at the Nuclear Medicine Department of Ghaem Hospital in Mashhad, from May 2017 to February 2018 with the support of Mashhad University of Medical Sciences, Iran.

No significant difference was noted in the mean age between case (differentiated thyroid cancer) and control groups (P=0.9). The two groups were also statistically similar in terms of pregnancy frequency (P=0.05) and number of alive children (P=0.8). Abortion seems to be the only item in DTC patients which was more than healthy sisters (0.2 versus 0.7) (P=0.003). However, this statistical difference showed no direct relationship with radioiodine treatment (RIT). As in DTC patients before and after RIT, no significant difference has been detected in DTC patients before and after RIT (P=0.48). Birth weight was not statistically different in DTC patients before and after RIT (P=0.66) and between DTC patients and their healthy sisters (P=0.2).

Radioiodine therapy for differentiated thyroid carcinoma has no considerable negative impact on pregnancy, whether on fertility rate or on gravity complications.