[Rearrangement of the RET gene in papillary thyroid carcinoma]

The RET/PTC oncogenes, activated forms of the RET protooncogene, almost exclusively found in papillary thyroid carcinoma (PTC). What is more, the targeted expression of RET/PTC in mice leads to the development of thyroid tumors very similar to human PTCs. In all RET/PTC types the RET tyrosine kinase domain is fused to the N-terminus of ubiquitously expressed genes that is capable of ligand-independent dimerization. The majority of RET/PTC identified consists of two types which results from the inversion of chromosome 10: RET/PTC1 and RET/PTC3. The prevalence of RET/PTC in papillary thyroid carcinomas of thyroid varies widely from a few to about 80% with the highest frequency in tumors arising in children after ionizing radiation. In Polish population the frequency of RET rearrangements in papillary cancers is 27%, although, it was reported to be twice higher in young patients (50% in patients younger than 21 at operation). Correlation with clinical outcome as well as prognostic value of RET/PTC is controversial. Some authors suggest that it predicts metastases, others found rearranged RET in more favourable, slow growing tumors. RET/PTC3 seems to be associated with solid/follicular variant PTC and short latency period (it is found more frequently in children) whereas RET/PTC1--with classic PTC variant and long latency.