Abstract

The risk of developing thyroid cancer increases considerably after exposure to external or internal radiation, especially in children below the age of 10. After the Chernobyl reactor accident, the yearly incidence of childhood thyroid cancer in Belarus increased to approximately 40 per 1.000.000 in girls and to roughly 20 per 1.000.000 in boys compared to approximately 0.5 cases per 1.000.000 prior to the accident. Typically, young children with thyroid cancer after radiation exposure present in ≈95% of the cases as papillary cancers, in ≈50% as invasive tumors growing outside the thyroid capsule, in ≈65% with lymph node metastases and in ≈15% with distant metastases. A joint Belarusian-German project starting in April 1993 that combined treatment with surgery and radioiodine was organized in 237 selected children from Belarus who were exposed to the Chernobyl fallout and had advanced stages of thyroid cancer. The study group included 141 girls and 96 boys. Their median age at the time of the accident was 1.7 years; whereas the median age at the time of diagnosis was 12.4 years. With the exception of two cases with follicular histology, the majority of the patients had been diagnosed with papillary thyroid cancers. In 63%, the tumor had grown outside the thyroid capsule and invaded the tissue of the neck (pT4). Nearly all of the selected cases (96%) showed-up with lymph node metastases (pN1) and 43% of the patients with distant metastases mainly to the lungs (pM1). In 58% of the children, complete remissions of thyroid cancer could be achieved until December 31st 2010 and in 34% of the children, stable partial remissions; in the remaining 8% of the patients, partial remissions were observed. The risk of radiation-induced thyroid cancer increased considerably in children and adolescents who were affected by the Chernobyl reactor accident. In spite of the fact, that thyroid cancers in young children seem to behave more aggressively than in older patients, the results of combined treatment with thyroidectomy, radioiodine therapy and thyroid hormone replacement are excellent.

Highlights

  • The risk of developing thyroid cancer increases considerably after exposure to external or internal radiation, especially in children below the age of 10

  • The risk of radiationinduced thyroid cancer increased considerably in children and adolescents who were affected by the Chernobyl reactor accident

  • According to a comprehensive review published by UNSCEAR on the occasion of the 25th anniversary of the Chernobyl accident, the main tremendous health effect of radiation from the accident observed until today is a dramatic increase of the incidence of thyroid cancer in persons exposed as children or adolescents [8,9,10,11]

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Summary

Historical Perspective

It is well known from the past, that external radiation can induce thyroid diseases such us hypothyroidism, autoimmunity, nodules and cancer [1]. With respect to the exposure to ionising radiation after a nuclear reactor accident, the observations in long-term survivors from the atomic bomb detonations in Japan are appropriate [4,5]. A lesser, but still highly significant risk was found in adolescents from 10–20 years, no significant increase of thyroid cancer risk was observed in adults above the age of 20. This is not surprising, since age dependent thyroid dose factors for I-131 range from 36 in newborns to 1.4 in adults according to model calculations [7]

The Chernobyl Accident
Epidemiological Studies after Chernobyl Regarding Thyroid Cancer
Ultrasound Screening
Surgical Treatment
Radioiodine Therapy in Germany
Patients
Radioiodine Treatment
Treatment Response
Discussion
Findings
Conclusions
Full Text
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