Radiation exposure and thyroid cancer: a review

Abstract

The association between radiation exposure and the occurrence of thyroid cancer has been well documented, and the two main risk factors for the development of a thyroid cancer are the radiation dose delivered to the thyroid gland and the age at exposure. The risk increases after exposure to a mean dose of more than 0.05-0.1 Gy (50-100mGy). The risk is more important during childhood and decreases with increased age at exposure, being low in adults. After exposure, the minimum latency period before the appearance of thyroid cancers is 5 to 10 years. Papillary carcinoma (PTC) is the most frequent form of thyroid carcinoma diagnosed after radiation exposure, with a higher prevalence of the solid subtype in young children with a short latency period and of the classical subtype in cases with a longer latency period after exposure. Molecular alterations, including intrachromosomal rearrangements, are frequently found. Among them, RET/PTC rearrangements are the most frequent. Current research is directed on the mechanism of genetic alterations induced by radiation and on a molecular signature that can identify the origin of thyroid carcinoma after a known or suspected exposure to radiation. Arch Endocrinol Metab. 2017;61(2):180-7.

Radiation and Second Primary Thyroid Cancer Following Index Head and Neck Cancer

“…Our study aimed at describing the rate of SPTC following HNC and evaluating the increased risk associated with this development following HNC radiation therapy. Consistent with other studies, we determined that the risk of SPTC following index HNC was low . We did, however, find that treatment modality, including radiation alone or radiation in combination with other treatments, did not significantly increase the risk of SPM.…”

“…The mean age of the patients in our cohort was 61.5 years; therefore, it is possible that many did not live long enough after their radiation treatment for their primary HNC to develop SPTC. This is plausible, as the mean time between a primary cancer and developing SPTC was found to be between 6 and 30 years . This study cohort's latency period was consistent with these values, with the time to SPTC ranging from 1 to 39 years after HNC diagnosis.…”

Pathological characteristics of thyroid glands from Japanese Black Cattle living in the restricted area of the Fukushima Daiichi Nuclear Power Plant accident

“…Most radiation-induced thyroid cancers were papillary thyroid carcinomas (Kazakov, Demidchik, & Astakhova, 1992). The radiation dose and age at exposure are the primary risk factors for the development of thyroid cancer (Iglesias et al, 2017). At 8 years after the nuclear power plant accident in the Fukushima Prefecture, an increase in the incidence of pediatric thyroid cancer remains a concern.…”

The effect of TP53 and P21 gene polymorphisms on papillary thyroid carcinoma susceptibility and clinical/pathological features

“…Therefore, many other factors, which modified the sensitivity to the development of thyroid carcinoma were suggested. These factors include radiation dose, age, and latency, Iodine status and personal and familial susceptibility …”