Tyrosine kinase expression is increased in papillary thyroid carcinoma of children and young adults

Tyrosine kinases (TKs) are important candidate genes for malignant transfor mation and at least 21 different TKs have been identified in the thyroid gl and. We hypothesized that the collective activity of these TKs might be inc reased in thyroid carcinoma and have association with the clinical behavior of individual tumors. To test this, we determined TK expression by immunoh istochemistry in 74 archival thyroid tissue blocks (48 papillary thyroid ca rcinoma, PTC; 9 follicular thyroid carcinoma, FTC; 17 benign thyroid diseas es) from children and young adults. Mean TK expression was greater for PTC (2.1 +/- 0.11) than benign lesions (1.6 +/- 0.2, p = 0.027), and also tende d to be greater in ETC (2.1 +/- 0.25, p = 0.12). Recurrence risk was three- fold greater for PTC with intense TK expression (4/15, 27%) than for PTC wi th minimal - moderate TK expression (3/33, 9.0%). However, this was not sta tistically significant (p = 0.10). In PTC, TK expression correlated with ex pression of the receptor for hepatocyte growth factor/scatter factor (cMET, r = 0.31, p = 0.044). In FTC, TK expression did not correlate with cMET, b ut tended to be greater in young patients (r= -0.59, p = 0.09). We conclude that TK expression is increased in PTC and possibly associated with an inc reased recurrence risk.