Relevance of iodine intake as a reputed predisposing factor for thyroid cancer

摘要: ABSTRACT Iodine is a trace element that essential for the synthesis of thyroid hormone.Both chronic iodine deficiency and excess have been associated withhypertrophy hyperplasia follicular cells, attributed to excessive secretion ofTSH. This may be cancer risk, particularly in women. Exper-imental studies documented induction by elevation ofendogenous TSH, although small number animals. asso-ciated with carcinogenic agents chemical mutagens will result higher inci-dence malignancy. Inadequate low intake increasedTSH stimulation, increased cell responsiveness thyroidcell EGF-induced proliferation, decreased TGF β1 production angio-genesis, all phenomena related promotion tumor growth. Epidemiologicalstudies associating led controversial con-flicting results. There no doubt introduction universal prophylax-is population previously iodine-deficiency leads changing pat-tern more prevalent papillary declining thyroidcancer. Also anaplastic practically not seen after years iodinesupplementation. has also indicated as possible nutritionalfactor prevalence differentiated Iceland, Hawaii and,more recently, China. In conclusion: available evidence from animal experi-ments, epidemiological prophylaxis demonstrated shifttowards rise carcinoma, but clear relationship between overallthyroid incidence intake. (Arq Bras Endocrinol Metab2007;51/5:701-712)Keywords: Iodine; Thyroid cancer; deficiency; excess; Carcino-genic agents; Environmental effect