INCIDENCE AND CLINICAL CHARACTERISTICS OF THYROID-CARCINOMA AFTER IODINE PROPHYLAXIS IN AN ENDEMIC GOITER COUNTRY

Iodized salt prophylaxis has been performed in Austria since 1963. Thr ough this approach, mean urinary iodine excretion has been normalized to 144 +/- 23.5 mu g/g creatinine per day. Thus Tyrol is no longer an endemic goiter area. We have analyzed the impact of iodized salt proph ylaxis on thyroid cancer (TC) comparing data from the early 1960s with those corresponding to the period 1986 to 1995, when iodine supply wa s normalized. The study included 439 patients from Tyrol and Southern Tyrol. The incidence of TC in Tyrol has risen during the past decades from 3.07 between in 1957 and 1970 to 7.8 between 1990 and 1994 (CR/10 0000/year). We observed a rise in the percentage of differentiated ade nocarcinomas (56% to 91.5%) with a predominance of papillary TC (54.4% ) along with a decrease of anaplastic TC, In addition to these histolo gical features, a shift to less advanced TNM stages, eg, T1-3, N0-1a, M0, was obvious, increasing from 29% to 72.2%, whereas advanced tumors , ie, T4 or N1b or M1, decreased from 71% to 28%. These changes have s ignificantly improved prognosis. The current 5-year survival rate is 9 0.7% as compared with a rate of 73% in the 1960s; the values for 7-yea r survival are 89% and 48%, respectively. The marked effects of age, t umor stages, and histology on prognosis were confirmed with the Kaplan -Meier method. We conclude that together with normalization of iodine supply in an endemic goiter region the epidemiological profile of TC h as changed. Even though the incidence of TC has risen, prognosis has s ignificantly improved due to a shift towards differentiated forms of T C that are diagnosed at earlier stages.