Epidemiologic and clinical evaluation of thyroid cancer in children from the Gomel region (Belarus).

This study reviews the epidemiology of thyroid cancer during childhood from the environs of Gomel in Belarus and the clinical data of 64 children aged 4 to 16 years from this area who had been diagnosed with differentiated thyroid carcinoma following the nuclear accident of Chernobyl. One case of thyroid cancer in children (aged < 15 years at diagnosis) was observed during the period 1981-1985 (rate = 0.5; expressed as annual averages per million children under age 15 years in the region of Gomel and period identified) before the Chernobyl accident. Twenty-one cases of thyroid cancer in children were observed during 1986-1990 (rate = 10.5) and 143 (rate 97) during 1991-1994 after the Chernobyl accident. During the first 7 months of 1995, there were 33 more cases of thyroid cancer observed in children. Three children with thyroid cancer were born since 1986 in the Gomel region. A total of 64 children aged 4 to 16 years from this area who had been diagnosed with differentiated thyroid carcinoma had been reviewed by us during the period May to November 1994. The female/male ratio was 1.4:1.0. At the time of the first diagnosis the mean age of the children was 9.4 +/- 2.8 years, and at the time of the accident their mean age was 3.8 +/- 2.4 years. More than 90% of the patients were less than 6 years of age and 3 were still in utero at the time of the accident. The period of latency between the accident and the first diagnosis was 5.6 +/- 1.5 years. Their ages at the time of the first diagnosis and their ages at the time of the accident were significantly correlated (p = 0.001); there was no significant correlation between the age of each child at the time of the accident and the latent period before the onset of carcinoma. The aggressiveness of the tumor, evaluated on the basis of T stage, lymph node status, and lung metastases, did not correlate with age at the time of the first diagnosis or with the age at the time of the accident. The susceptibility of the thyroid to the carcinogenetic effects of radiation, particularly during the first years of life (< 5 years) has clearly been demonstrated. However, there appears to be no correlation between the aggressiveness of the tumor and the age of the patients.