Malformations in the offspring of women with thyroid cancer treated with radioiodine for the ablation of thyroid remnants

Abstract

Rationale: Since ovarian function is only temporarily compromised by radioiodine therapy, many women with thyroid cancer treated with radioiodine can become pregnant. The present study evaluated the evolution of these pregnancies and the consequences for the offspring. Patients and methods: We retrospectively analyzed 78 pregnancies of 66 women submitted to total thyroidectomy, followed by radioiodine therapy (3.7-5.5 GBq 131 I, mean 4.64 GBq). In all patients, conception occurred one year after ablative therapy (mean of 30 months). Age ranged form 19 to 36 years (mean of 30.6 years) at the time of radioiodine treatment and from 23 to 39 years (mean of 32.8 years) at the time of conception. Results: Four (5.1%) of the 78 pregnancies resulted in spontaneous abortions. Three (4%) of the 74 deliveries were preterm and there was no case of stillbirth. The birthweight was > 2500 g in 94.6% of the children (mean ± SD: 3350 ± 450 g) and only one infant (1.3%) presented an apparent malformation at birth (intraventricular communication). No difference in the age at the time of radioiodine therapy or conception or in radioiodine dose was observed between pregnancies with an unfavorable outcome and those with a favorable outcome. Conclusion: We conclude that pregnancies that occur 12 months after ablative therapy are safe. RESUMO Malformações na Prole de Mulheres com Câncer de Tireóide Tratadas com Radioiodo para Ablação de Remanescentes Tireoideanos.Arrazoado: Uma vez que a função ovariana está apenas temporariamente comprometida pela terapia com radioiodo, muitas mulheres com câncer de tireóide tratadas com radioiodo podem engravidar. O presente estudo avaliou a evolução dessas gravidezes e suas conseqüên-cias para a prole. Pacientes e métodos: Analisamos retrospectivamente 78 gravidezes de 66 mulheres submetidas a tiroidectomia total seguida de radioiodoterapia (3,7-5,5 GBq 131 I, média 4,64 GBq). Em todas, a concepção ocorreu um ano após a terapia ablativa (média de 30 meses). A idade variou de 19 a 36 anos (media de 30,6) à época do tratamento com radioiodo e de 23 a 39 anos (média de 32,8) na época da concepção. Resultados: Quatro (5,1%) das 78 gravidezes resultaram em abortamento espontâneo. Três (4%) dos 74 partos foram pré-termo, mas não houve nenhum natimorto. O peso ao nascer foi >2.500 g em 94,6% das crianças (média ± DP: 3.350 ± 450 g) e somente uma delas (1,3%) apresentou uma malformação aparente ao nascimento (comunicação intraventricular). Nenhuma diferença quanto à idade na época da radioiodoterapia ou na concepção ou na dose de radioiodo foi observada entre as gravidezes com ou sem um desfecho favorável. Conclusão: Gravidezes que ocorrem 12 meses após terapia ablativa com radioiodo são seguras.

Perinatal outcomes in post-thyroidectomy pregnancies

“…Indeed, adverse perinatal outcomes were demonstrated in the postthyroidectomy group as compared to hypothyroidism due to other causes group and as compared to normal pregnancies. This stands in contrast to previous studies [2][3][4][5][6]9], in which complete thyroidectomy was not found to influence perinatal outcomes, and bare significant clinical importance as to counseling and management of such pregnancies.…”

“…Previous studies [8] have found adverse perinatal outcomes for hypothyroidism pregnancies; nevertheless, these studies did not investigate perinatal outcomes for patients following complete thyroidectomy. Previous studies about post-thyroidectomy pregnancies deal mostly with the effects of radioiodine treatment on perinatal outcomes [2][3][4][5][6]9], but not about the effects of hypothyroidism itself due to complete thyroidectomy.…”

“…All patients were advised to avoid conception during the first year post-ablation. Pregnancies which occur after 12 months after ablative therapy have no increase risk for abortion, prematurity or malformation of the offspring [3]. Likewise, Balevonic et al [4] and Bal et al [5] concluded that there is no reason to discourage patients treated with 1-131 from becoming pregnant after 1 year.…”

Effects of I-131 therapy on gonads and pregnancy outcome in patients with thyroid cancer

“…Specifically, only four (5.1%) of the 78 pregnancies resulted in spontaneous abortions, three (4%) of the 74 deliveries were preterm, and there was no case of stillbirth. The birth weight was >2,500 g in 94.6% of the children, and only one infant (1.3%) presented with a congenital malformation at birth (intraventricular communication) (44). A similar retrospective study in 76 women treated for DTC from 1971 to 2005 reported 49 pregnancies after I-131 therapy.…”

The preliminary clinical observation and analysis of childbearingage women with a history of iodine-131 treatment for Graves' disease

“…Previous studies in female patients have shown no significant effects of iodine-131 in treating thyroid cancers on fertility rate, birth weight, or congenital anomalies in offspring (22)(23)(24)(25)(26)(27)(28)(29). In our study, we have the same experience in treating patients for GD.…”