-/l6iTads
in children and 350 in the adults.
Oniy 2 cr 19 children expes ed under the 2 sé
7
=
Tm 17
of 10 deveioped frank clinic
al Wepetnyroidism and that required a nu mner of vears tc
become evident.
This raised a question whether the estimate of the dose in the Mar-
Shallese was too low.
Both children were irradiated at about 1 yeaf of age.
of these has developed nodules.
Neither
Presumably, cellular damage was su fficiently great
to preclude thyroid cell replication.
Of the other 17 children who were exposed,
15 did not display clinical hypothyroidism but have developed neopl hsms and been
operated.
Our experience finding carcinomas in radioiodine treated pati
ts in the National
Cooperative Thyrotoxicosis Therapy Follow-Up Study seems to be qui e contrary to the
Marshallese experience.
An unusually small number of carcinomas
considerably fewer than would have been expected, considering the
number of occult malignant lesions found in Graves' disease treat
s found; in fact,
elatively larger
by surgery.
Such
incidental lesions found at surgery might have been expected to g
w if unknowingly
left in place and 131, treatment had been given.
tween the doses
The difference
received by the Marshallese thyroids and those of Graves' disease fi s considerable.
Graves' disease patients usually receive 5,000 to 14,000 rads whi
the adult Mar-
shallese received an estimate of 550. Furthermore, the hyperplasti
gland of Graves'
disease would be expected to be far more sensitive to the radiati m than the normal
glands of the Marshallese.
Our animal experiments and the most recent studies of other investigators using
rats seem to have suggested strongly that it is the smaller doses
circumstances under which neoplasms arise.
Indeed the effects ar
0 f£
131, that produc
sufficiently mild
so that no microscopic architectural distortion is recognized in he thyroids most 1
Ciined to develop neoplasms.
In our studies we have shown that there was a failure of the moderately irradia’
Tat thyroid to hypertrophy when stimulated by giving an antithyrs id substance.
We hh:
also shown in such thyroids that there is a marked reduction in fhe capacity of such