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Nate anode sacheegetarnat cat benscatas
Bowie dt.
Fiuure 47
Relationship af divroid dese ta age when le.tualignant,
Abts develop in Muarslidlese. @. Benin: .
ceived their dose largely from radiviodines, and
the groups receiving x-irradiation, ‘Vhese data are
not eatensive enough to showpossible threshold
effects. Since in animal experiinents | Tis only
about tin tea “45 as effective as x-irradiation in pro-
ducing thyroid: tumors*4.120.129.190 why do the
Marshatiese data indicate near equality of efleci?
His estimated that thousands of children have received diagnostic UT (20 to 50 wCiiin the past resulting in thyroid deses up to hundreds of rads.
hy pathvroidisai develops, the cases of thyroid can-
corarefewer than expected, 141s Beebe *'Vhe development, in the two stunted Marshallese bows, of
thyroid atrophy with bypothyroaidisiy but without
the developanent of tumears isin fare with this rea soning. Odserting. samen hat, the urcater incidence
aft thyroid cancer iuecbildren is the finding that children survive longer than older people, even with
the well dillerenuiatedl ty pes he
‘Vhe possible clfeets of the stress of puberty in
the development of disci lesions lave been previously noted.) The stress of frequent pregnancies, which had aceurred before the development
of malignant lesions in the three Rongchip wonen,
aay have been a hector ia development of neo-
plasin, Both these carcclitions, however. may be
fortuitaus.
2. Comparison of Thyroid Neoplasias From
X-Ray Radiation and Radioiodine Irradiation
The data in Tables US aud sa show that the risk
per rad for the developimacat of thyreid neoplasms
in the Marshallese was quite similar to that ia
populations exposed to x-irradiation. Vhe data in
Figure 44 indicate a haear relationship beoveen
nodulariay in the Afarstatiese children, whe re-
yetonly bcase with thyroid tumors has been reported. FUE CS. Public Health Service workers
recently reviewed a large number of case historics
of people who had received radioiodines for treat
ment of hyperthyraidisin. 2? They were unable to
shoay any clear-cut increase in incidence of thyroid
lumors in this group compared with a group
treated by surgical thyroidectomy. Encreasing
numbers of the pauients treated with !VT devel:
oped Varying degrees of hypoth vroidisar inlater
years. The lose incidence of tumurs following such
treaument may be related to the high doses of
radiation given to the chvreid, sullicient to destroy
ils reveneralive capacity.
In should be noted, however. that in the past
few vears a number of thyroid malignancies have
heen reported follawing radioiodine therapy tor
hyperthyroidism hl Phe number of cases reparted is lower than expected on vhe basis ofdos.
ave tothe thyroid, The increased tumorigenesis in
the Marshallese may be related tothe nature of the
radiation. more than halfithe dose being due to
short-lived isotopes of iodine (particularly EET,
Ve and “ty which are more energetic (see Ap-
pendix 9C). Vasilenko and Rlassayskiit\? have
demonstrated that when these shorter-lived isotapes af iodine are combined with 17 the tumori-
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