T r Thivreaed chow (tyaedst VD py ph T t 4 a wee mm Kemerlap le CZ) Ablunar L C) Crea £ % = = = Mawel : T T TTT @ birrugn \ 4 Mahiqnatt \ 1 ** t i 1 i * t al = , ' ; 1 . : e 1 +t \ oe "iC4 iu 4 Hie { 2 - 4 t | : | - ' .- hs be ! l | J i j -‘ ti - e4 "y as lw i| ty : : a:frhtt: ; I dan | if at : ilo: wi - Ibeai ww at ¥ wD 4 e yr.U wr 4H) e ; Ww e . j Lr Ae i“) bd ; Age at developine nt uf koiets 5 z = T Ss L tdir i \ z 2 T “4 \ = 7 =z woe ! io rte ii1 {i a | at a ae 70 aed | iw 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- 4 4 ‘ d q