Epidemiology and therapy of thyroid cancer in childhood and adolescence.

Thyroid cancer is a rare disease in childhood and adolescence. However, it represents the most frequent cancer type in this age group. Thyroid cancer amounts about 0.5%-1.5% of all malignancies in children and adolescents. In Germany 10-30 cases could be expected in a year. The most common histologic type for this age group is the differentiated thyroid cancer (DTC), i.e. the papillary and follicular subtypes (90%). In 10% of patients medullary thyroid cancer (MTC) will be diagnosed. DTC occur more often in girls than in boys (female/male-ratio 2:1), with a median age of about 12-13 years (yrs). An important aetiological factor of DTC is a former exposition to different kinds of radiation. In childhood and adolescence MTC mostly appears in patients suffering from the syndrome MEN-2, whereas the sporadic form is rare. As in DTC, more girls than boys can be diagnosed for MTC (female/male-ratio 2-3:1), with a median age about 10 yrs. The anaplastic/undifferentiated subtype occurs extremely rare. For all types of thyroid cancer the most important therapeutic approach is the surgical intervention. In most cases of DTC an optimal disease control could be achieved by radioiodine therapy. Prognosis of DTC in children and adolescents is favourable. However, therapeutic strategies and modalities reported in the literature are very different. In contrast, prognosis of MTC is rather poor, that of the anaplastic type is infaust. No other effective therapy option than surgery is available. To evaluate the therapeutic efficacy of a combined modality therapy by both radiotherapy and cytostatic drugs in children and adolescents with poor prognosis types of thyroid cancer, an interdisciplinary multicenter therapy study will now be started in Germany.