Differentiated thyroid cancer in children and adults: same or distinct disease?

Differentiated thyroid cancer (Dtc) is a rare disease, especially in children. Differences in the biology and clinical course of Dtc in children, when compared with adults, may be related both to pathogenesis as well as to clinical outcome of the disease. In childhood, the thyroid gland exhibits higher susceptibility to the carcinogenetic effect of ionizating radiation than in adulthood. Papillary thyroid cancer (Ptc) is more prevalent in children in comparison to adult patients. Among molecular events known to occur in papillary thyroid carcinoma, rEt/Ptc rearrangements exhibit higher prevalence in younger patients, while brAF mutations are very rare in this age group. cancer disease presents at a more advanced stage: 1) primary tumour at diagnosis is larger, especially in relation to the volume of the whole gland; 2) neck lymph node involvement is more commonly observed; 3) distant metastases are detected 3-4 times more frequently than in adults. the lungs are almost the sole distant metastatic site in children and pulmonary metastases are nearly always functional. Additionally, recurrence rates tend to be higher in children; nevertheless, cause-specific cancer mortality remains low. Up to now, thyroid cancer guidelines have been formulated on the basis of experience gained in the general population of patients. the peculiarities in childhood disease raise the question of whether it should be considered a distinct subtype, with specifically tailored therapy recommendations. A definitive answer to this question is not possible with the present state of knowledge. In the opinion of the authors, molecular analyses of childhood thyroid cancer may be crucial, as the clinical data have not satisfactorily answered this question.