engleski

Changing trends in incidence and mortality of thyroid cancer in Croatia 1968 - 2002

Over the past 35 years increasing incidence rates of thyroid cancer were recorded in Croatia, with 8-fold increase in age-standardized rates per 100000 in females (from 1.1 to 8.9), and 2.5-fold in males (from 0.8 to 2.0) mostly from a rise in papillary cancer. At the same time, age-standardized mortality from thyroid cancer in Croatia remained stable at low levels (0.32 in males, 0.43 in females, per 100000). The activity of radioactive fallout that contaminated the Croatian territory in 1986 was estimated to be approximately 5.2x1015Bq, about 0.28% of the total activity released as a consequence of the Chernobyl accident. Fetal thyroid doses (30 cases at autopsy) were about hundred times lower than the possible threshold value, therefore it was concluded that a risk of child born with harmful trait was negligible. The average annual dose in 1986 in Croatia was 15% larger than the average dose calculated for the period 1982-1985 (p=0.01). The satisfactory iodine prophylaxis in Croatia was an important protection against radioiodine for Croatian population. After 1986, there was no increase in childhood thyroid cancer in Croatia, and only 16 sporadic cases were observed in children aged 0-14 years during the entire period of 16 years after the accident. In 1996, new regulation on salt iodination with higher iodine content was introduced, changing pathohistological patterns of thyroid cancer. The great majority of the increase in incidence of thyroid cancer in Croatia is considered to be a result of improved diagnostics, especially introduction of ultrasound guided fine needle biopsy. No significant difference in trends of thyroid cancer incidence before and after the Chernobyl accident has been observed in children and adolescents in Croatia. Levels of ionizing radiation in Croatia caused by Chernobyl accident were too low, and impact on thyroid cancer incidence in Croatia is probably negligible.

thyroid cancer; Chernobyl accident; iodine prophylaxis

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