Exposure to ionizing radiation in adulthood and thyroid cancer incidence.
ABSTRACT Recent reviews of the radiation epidemiology literature have concluded that there is little evidence that exposure to ionizing radiation in adulthood causes thyroid cancer. This paper examines the association between radiation dose and thyroid cancer incidence among Japanese survivors who were adults at the time of the atomic bombings of Hiroshima and Nagasaki.
Analyses were conducted using data on cancer incidence during the period 1958-1998 among 59,687 members of the Life Span Study of atomic bomb survivors who were 20 years or older at time of bombings of Hiroshima and Nagasaki. Poisson regression methods were used to derive estimates of associations between thyroid dose in gray (Gy) and thyroid cancer incidence by sex, age at exposure, and time-since-exposure.
The number of thyroid cancer cases among women (n = 241) was nearly 5-fold the number of cases among men (n = 55). Estimated thyroid dose was positively associated with thyroid cancer incidence among women A-bomb survivors (excess relative rate/Gy = 0.70; 90% confidence interval = 0.20-1.46). In contrast, a negative association was observed between thyroid dose and thyroid cancer among men (excess relative rate/Gy = -0.25; <0 to 90% confidence interval = 0.35). The association among women was positive for all time-since-exposure periods examined but tended to diminish in magnitude with time-since-exposure.
Exposure to ionizing radiation in adulthood was positively associated with thyroid cancer among women A-bomb survivors, although the risk seems to be lower than for those exposed to radiation in childhood.
- SourceAvailable from: David Goldenberg
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ABSTRACT: Objectives/HypothesisTo determine whether there is an association between radon levels and the rise in incidence of thyroid cancer in Pennsylvania.Study DesignEpidemiological study of the state of Pennsylvania.Methods We used information from the Pennsylvania Cancer Registry and the Pennsylvania Department of Energy. From the registry, information regarding thyroid incidence by county and zip code was recorded. Information regarding radon levels per county was recorded from the state. Poisson regression models were fit predicting county-level thyroid incidence and change as a function of radon/lagged radon levels. To account for measurement error in the radon levels, a Bayesian Model extending the Poisson models was fit. Geospatial clustering analysis was also performed.ResultsNo association was noted between cumulative radon levels and thyroid incidence. In the Poisson modeling, no significant association was noted between county radon level and thyroid cancer incidence (P = .23). Looking for a lag between the radon level and its effect, no significant effect was seen with a lag of 0 to 6 years between exposure and effect (P = .063 to P = .59). The Bayesian models also failed to show a statistically significant association. A cluster of high thyroid cancer incidence was found in western Pennsylvania.Conclusions Through a variety of models, no association was elicited between annual radon levels recorded in Pennsylvania and the rising incidence of thyroid cancer. However, a cluster of thyroid cancer incidence was found in western Pennsylvania. Further studies may be helpful in looking for other exposures or associations.Level of EvidenceNA Laryngoscope, 2014The Laryngoscope 07/2014; · 2.03 Impact Factor