A case-control study of papillary thyroid cancer in children and adolescents.

Thyroid carcinomas in children and adolescents are rare tumors and the most common among them is papillary thyroid cancer (PTC). Its etiology is still under research and has not been clearly defined thus far, especially in young individuals. The aim of this case-control study was to determine potential risk factors for the development of PTC in children and adolescents. This type of study has not been carried out previously in this age group. A case-control study was carried out during a 15-year period, between 1995 and 2009. The case group included 75 patients with PTC younger than 20 years of age, with the youngest patient being 6.5 years old; 45 patients were female and 30 were male. The control group included the same number of participants, and the cases were individually matched by sex, age, and place of residence. Conditional univariate and multivariate logistic regression methods were applied in data analysis. According to univariate logistic regression analysis, PTC in children and adolescents was significantly related to the following factors: family history of thyroid cancer, family history of residence in an endemic-goiter area, family history of benign thyroid disease, and family history of nonthyroid malignant tumors. According to the multivariate logistic regression method, PTC in children and adolescents was independently related to a family history of thyroid cancer (odds ratio=4.5, 95% confidence interval=1.2-19.8) and a family history of nonthyroid malignant tumors (odds ratio=3.8, 95% confidence interval=1.4-8.7). In conclusion, all of the factors associated with the development of PTC in children and adolescents were related to their family history.