Document DDwNp2a4k7D5qgRk2E178RJB5

HFM -003511 No. of patient* 1940-1949 1960-1959 1960-1964 1965-1969 ^ Male Female Male Female Male Female Male Female -: 197 600 674 1803 416 989 392 1053 J Percent at 3 yaan 64 72 73 84 80 87 80 88 > Percent at 6 years 61 69 73 83 78 87 -- Percent at 10 yean 48 68 73 83 Parcant at 16 year* 48 68 '' Source: End Results In Cancer, Report No. 4, End Results Section, Biometry Branch, National Cancer Institute, 1972, p. 162. and carcinoma of the colon, osteomas and sebaceous cysts,45 The multiple ham artoma syndrome (Cowden's disease) is an analogous disorder first described by Lloyd and Dennis in 1963.44-4* Patients with this autosomal dominant disorder exhibit some form of thyroid neoplasia, most often as goiter or multicentric ade nomas, but in some cases as carcinoma. Other prominent familial features of this syndrome include mucocutaneous papil lomas, lichenoid keratoses of the face, neck, hands and forearms, angiomas, subcutaneous and retroperitoneal lipo mas, ovarian cysts, fibrocystic disease and carcinoma of the breast. Adenoma tous, metaplastic or inflammatory polyps and ganglioneuromas of the gastrointes tinal tract have been described. Iodine Deficiency as a Cmfactor In Thyroid Carcinogenesis In experimental animals such as rats, mice, and, Syrian hamsters, chronic io dine deficiency may eventuate into carci noma of the thyroid after a succession of pathogenic events which include intense follicular hyperplasia, hypertrophy and nodule and adenoma formation. The evi dence in man for an etiologjc association between severe iodine deficiency and thy- . roid cancer has consisted of increased thyroid cancer incidence and mortality^ particularly of the follicular and anaplas tic types, in geographic areas considered to be.at high risk for adenomatous or nodular goiter. The foci of carcinoma have usually been located in otherwise normal parenchyma rather than within hyperplastic nodules.4*.41 It has even bee? suggested that the frequency of goiter asp thyroid cancer in Switzerland diminished after the introduction of iodized table saifi Those who argue against a direct causal relationship between endemic goiter and thyroid carcinoma point to prior studiesin geographic areas where, there was no -.correlation (i.e., Australia,. Austria,^ Fin land and the United States), or where the frequency of goiter was low and thyroid cancer was high (i.e., Hawaii, Iceland and Newfoundland). ^Other reports from Switzerland subsequent to the introduc- HG01 6906 CA-A CANCER JOURNAL FOR CLINICIANS , All Ages : Under 25 26-44 Male Female Male Female Male Female Percent at S year* Percent at 10 year* 75 86 96 99 , 92 SB 74 86 ' 96^ 99 91 96 45-54 55-64 654- Male Female Mala Female Male Female Percent at 6 year* > 76 91 61 67 ..- 39 46. Percent at 10 years : 70 89 49 65 33 ' 44 Source: End Riniult* In Ccmcar* Report f^o. ^Cnd RasuItt Section, Biometry BrsnciiV National Cancer lntltAite,1972, p. 1S4, ; tion of iodized table salt do not substanti ate a continuing trend of decreasing frequency of thyroid cancer, but rather emphasize the stable rates of thyroid can cer mortality, decreasing incidence- of goiter, and increasing proportion of thy roid cancers that are classified as papil lary.4,150 The observation of increased thyroid cancer mortality in ah endemic goiter area, i.e,, where the prevalence of goiter is 10 percent or greater, may be due to the higher proportion of anaplastic carcinomas.* In addition, thyroid en largement due to iodine deficiency may obscure the . existence of a cancer, and because of delay in seeking medical care, the majority of malignant tumors are diagnosed at more advanced stages.51 In studies conducted in the United States during 1939-1951, the average annual age- *lt has also been suggested that the highly ma lignant hemangioendothelioma of the thyroid occurs in geographic areas where iodine is de ficient. and panicularly in older patients with chronic goiter. (Cubilla, A.: Personal Com munication, 1977.) adjusted mortality due to thyrotoxicosis (secondary to toxic nodular goitehand the diffuse hyperplasia of Graves* Vdisease) diminished significantly in relation to the decreasing prevalence of endemic goiter; during the same period of time,-the ageadjusted mortality due to thyroid cancer increased slightly.52To summarize, the epidemiologic evidence that endemic io dine, deficiency may serve as a necessary and sufficient cause of the follicular type .of thyroid carcinoma is unconvincing, although iodipe prophylaxis mayjgher the histologic pattern of thyroid earner, and ultimately diminish the mortality due to thyrotoxicosis. Graves' Disease and-Hashlmpto's Thyroiditis The coincidence of thyrotoxicosis and thyroid cancer was considered (o be ex tremely rare. In more recent statistical surveys, the prevalence of thyroid carci. noma in patients with toxic goiter has been reported variously as being between 0.2 and 5 .O percent.55 The average prevalence VOL 28, NO. 2 MARCH/APRIL1978 P00i 0907