These findings indicate that up to a point,
perhaps in the range of 1500-2000 cGy, the
greater the radiation dose the greater is the
chance of a detected thyroid nodule being
cancerous.
60
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1984), and the prevalence does not increase with
age, in contrast to overt carcinomas and benign
lesions. In 23 unexposed Marshallese undergoing
thyroid surgery under the auspices of the
Brookhaven medical program, 2 (9%) had occult
carcinomas. Reports from the Atomic Bomb
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Relation of thyroid-absorbed dose to age at exposure categorized by nodule histology.
world (Fukunaga and Yatani, 1975; Harachet al.,
7
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60
0
Age at exposure in 1954 (yrs)
7) Did radiation increase the incidence of "occult"
carcinomas?
Occult thyroid carcinomas have been found in
6-36% of routine autopsies in many parts of the
1
7
Casualty Commission in Japan indicated that occult
thyroid carcinomas were increased by rddiation
exposure (Sampsonet al., 1969), although ere is
at least one subsequent study from Nagasgki that
found no such increase (Wakabayashi et alf 1983).
In the exposed Marshallese a similar effect ay also
be present, for based on results of urgical
exploration, 6 of 24 (25%) of Utirik ersons
exposed to radiation (thyroid-absorbed doses
ranging from 170 to 680 cGy) had occult
carcinomas. However, in the Rongelap group,
22.
60