A prospective study of thyroid nodular disease in children and adolescents in western Poland from 1996 to 2000 and the incidence of thyroid carcinoma relative to iodine deficiency and the Chernobyl disaster.

BACKGROUND: In Poland, where soil is deficient in iodine, supplementation of iodine was introduced in 1935, discontinued in 1980, and then re-introduced in 1997. One of the effects of inadequate iodine intake, prior to 1997, was an increase in the prevalence of thyroid nodular disease (TND) in children. Chernobyl, located in the neighbouring country of Ukraine, suffered a catastrophic nuclear explosion in April 1986.

PROCEDURE: A total of 411 children with TND (an incidence of 7.53/100,000) were diagnosed and registered in western Poland between 1996 and 2000 and further evaluated as a population-based study.

RESULTS: Based on the patient's clinical status, ultrasound examination, scintiscan, laboratory tests, cytology and the family history, many of the patients qualified for surgery and, as a result, histopathologic data were obtained from 155 of the 411 patients operated on to date (37.7% of all TND). Thyroid carcinoma was detected in 37 of the operated children, i.e. 23.9% or 9.0% of all children with TND with a median incidence of 0.68/100,000. Papillary carcinoma was the predominant histologic type (26-70.3%) compared to follicular carcinoma (10-27.0%) and medullary carcinoma (1-2.7%). Retrospective analysis of the figures for the 23 years (1972-1995) showed that in that period a total of 23 thyroid carcinomas were registered. However, only 12 of these were detected in the 20-year period between 1972 and 1991, none in the years 1992-1993 and, significantly, 11 from 1994 to 1995.

CONCLUSIONS: Thyroid carcinoma appears to be an ongoing and increasing problem in the children and adolescents of our region, and it is developing more intensively when compared, both to other parts of Poland and to previous statistics (2000 vs. 1985; P<0.002). Iodine deficiency and radiation resulting from the Chernobyl disaster might be important risk factors in the development of thyroid carcinoma in the young population analysed in our region in the period since 1994. The high percentage of follicular carcinoma and follicular adenoma with an undetermined prognosis (19 out of 46) indicates that the long-term iodine deficiency in our region may be more significant in the pathogenesis of malignant transformation than has previously been postulated.