Age-related activation of the tyrosine kinase receptor protooncogenes RET and NTRK1 in papillary thyroid carcinoma

Oncogenic rearrangements of RET and NTRK1 proto-oncogenes are frequently detected in papillary thyroid carcinomas. Several studies have shown an association between ionizing radiation and development of this tumor type. In addition in vitro irradiation of tumor cell lines induced rearrangements of RET similar to those observed in human papillary thyroid carcinomas. These two observations could be related to the reported increased incidence of papillary thyroid carcinomas in children living in contaminated areas around Chernobyl, given that it has been demonstrated that about 60% of them presents a RET oncogenic activation. However, this high frequency of RET positivity in radiation exposed children does not rule out the possibility that age could also play a role in the development of RET positive tumors. To assess this possibility we looked for a relationship between the presence of RET and NTRK1 oncogenic rearrangements and age at surgery in a sample of 92 consecutive patients. Our results show that, in papillary thyroid carcinoma, the frequency of RET and NTRK1 activation is significantly higher in the group of patients aged 4-30 years, thas supporting the concept that age could be contributing to this thyroid specific carcinogenic process.