Thyroid Cancer: Molecular Characteristics of Radiation-Associated Papillary Thyroid Cancer, with a Special Reference to of Atomic Radiation Exposure

Abstract

Among atomic-bomb (A-bomb) survivors of Hiroshima and , incidence of thyroid cancer significantly increased after exposure to nuclear radiation. This review will focus on the initiating gene alterations in the development of adult-onset papillary thyroid cancer (PTC) among A-bomb survivors. The effects of A-bomb radiation on chromosomal rearrangements (RET and NTRK1 rearrangements) and point mutations (BRAF and RAS mutations) after exposure were different. In contrast to PTC cases with point mutations, PTC cases with chromosomal rearrangements were observed more frequently among those exposed to high radiation doses compared to low doses, and these cases developed cancer earlier after exposure than did cases with point mutations. Interestingly, PTC cases with non-detected gene alterations were found more frequently among patients who were exposed to high radiation doses and who developed cancer earlier after radiation exposure than did the cases with BRAF point mutation. This suggests that heretofore non-detected gene alterations may also be involved in adult-onset PTC among A-bomb survivors.