Avaliação imuno-histoquímica da expressão de receptor de estrógeno β no carcinoma diferenciado de tireoide

Abstract

Differentiated thyroid cancer (DTC) is one of the most prevalent neoplasms and its incidence has increased in the last decades. The higher incidence of DTC in women of childbearing age suggests a possible involvement of hormonal factors in their pathophysiology. Estrogen influences the proliferation of neoplastic cells through the activation of its alpha (REα) and beta (REβ) receptors. REα promotes cell proliferation by reducing apoptosis, whereas REβ has the opposite effect. The relationship between the presence of these receptors in the DTC and the tumor behavior is unclear. The present study quantified the expression of β-estrogen receptors in DTC and normal thyroid tissue of patients of both sexes by immunohistochemistry and tested the association of this expression with clinical and tumor characteristics. We analyzed 79 tumors from 77 patients, of which 13 also had normal thyroid tissue analyzed. REβ expression was positive in 67% (53/79) of the tumors and in only 8% (1/13) of the normal thyroid tissues (p=0.002). REβ expression was associated with a higher risk of lymph node metastasis (84% vs 33%, p=0.007) and tendency to a greater risk of distant metastasis (21% vs 0%, p=0.14). No association between REβ expression and other clinical and tumor characteristics was found, including age (<55 years 70% vs. ≥55 years 63%, p=0.53), tumor size (≤1cm 59% vs.> 1cm 70% , p=0.35), histological type (papillary 68% vs. follicular 50%, p=0.59), variants (classical 68% vs. nonclassical 74%, p=0.63), capsule invasion 64%, p=0.69) and lymphatic invasion (absence 66% vs. presence 69%, p=0.77). Our data suggest that REβ expression in DTC may favor the metastatic capacity of thyroid tumor cells.