NtrkA Immunohistochemical Expression in Papillary Thyroid Carcinoma: A Clinicopathological Study

Background: Neurotrophin receptors are becoming more widely recognized as 
potential cancer therapeutic targets, although their clinical and pathological 
implications in thyroid cancer remain unclear. Examining neurotrophic tyrosine 
receptor kinase (Ntrk) fusions in papillary thyroid carcinoma (PTC) patient 
cohorts has offered information on the genetic basis of thyroid cancer.
Methods: This study included patients with PTC, thyroid adenoma, and 
multinodular goiter (MNG). The study aimed to investigate the association 
between the clinicopathological parameters and tropomyosin receptor kinase A 
(TrkA) expression in PTC patients and also to evaluate the 
immunohistochemical expression of TrkA in cases of thyroid adenoma and 
MNG, using immunohistochemistry streptavidin-biotin-technique. 
Results: This study comprised 77 cases in total, 27 cases with PTC, 13 with 
thyroid adenoma, and 37 cases with MNG, TrkA expression was not observed 
in adenoma or MNG cases, while expression was observed in 29.6% of PTC 
cases. TrkA expression differed significantly between instances of PTC, thyroid 
adenoma, and MNG (P<0.001). In PTC, there was a strong positive relationship 
between TrkA expression and T stage (P=0.002), lymph node involvement 
(P=0.004), and distant metastasis. There was no significant statistical difference 
in TrkA expression among patients based on their age or gender. 
Conclusion: TrkA expression is considered a negative prognostic marker, 
associated with tumor progression, advanced stages, and the presence of both 
lymph node and distant metastases, which may be valuable in assessing the 
aggressiveness of the tumor. TrkA could be a useful therapeutic target to reduce 
invasion and metastasis.