Thyroid cancer risk 40+ years after irradiation for an enlarged thymus: an update of the Hempelmann cohort

Although ionizing radiation is a known carcinogen, the long-term risk from relatively higher-dose diagnostic procedures during childhood is less well known. We evaluated this risk indirectly by assessing thyroid cancer incidence in a cohort treated with "lower-dose" chest radiotherapy more...

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Bibliographic Details
Published inRadiation research Vol. 174; no. 6; p. 753
Main Authors Adams, Michael Jacob, Shore, Roy E, Dozier, Ann, Lipshultz, Steven E, Schwartz, Ronald G, Constine, Louis S, Pearson, Thomas A, Stovall, Marilyn, Thevenet-Morrison, Kelly, Fisher, Susan G
Format Journal Article
LanguageEnglish
Published United States 01.12.2010
Subjects
Adult
Aged
Aged, 80 and over
Cohort Studies
Humans
Incidence
Middle Aged
Neoplasms, Radiation-Induced - etiology
Risk Factors
Sex Factors
Thymus Gland - pathology
Thymus Gland - radiation effects
Thyroid Neoplasms - epidemiology
Thyroid Neoplasms - etiology
Tomography, X-Ray Computed - adverse effects
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Summary:Although ionizing radiation is a known carcinogen, the long-term risk from relatively higher-dose diagnostic procedures during childhood is less well known. We evaluated this risk indirectly by assessing thyroid cancer incidence in a cohort treated with "lower-dose" chest radiotherapy more than 55 years ago. Between 2004 and 2008, we re-surveyed a population-based cohort of subjects treated with radiation for an enlarged thymus during infancy between 1926 and 1957 and their unexposed siblings. Thyroid cancer occurred in 50 irradiated subjects (mean thyroid dose, 1.29 Gy) and in 13 nonirradiated siblings during 334,347 person-years of follow-up. After adjusting for attained age, Jewish religion, sex and history of goiter, the rate ratio for thyroid cancer was 5.6 (95% CI: 3.1-10.8). The adjusted excess relative risk per gray was 3.2 (95% CI: 1.5-6.6). The adjusted excess absolute risk per gray was 2.2 cases (95% CI: 1.4-3.2) per 10,000 person-years. Cumulative thyroid cancer incidence remains elevated in this cohort after a median 57.5 years of follow-up and is dose-dependent. Although the incidence appeared to decrease after 40 years, increased risk remains a lifelong concern in those exposed to lower doses of medical radiation during early childhood.
ISSN:1938-5404
DOI:10.1667/RR2181.1