Fatores histopatológicos e moleculares em retinoblastomas enucleados
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Data
2013-12-17
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Universidade Federal de Goiás
Resumo
Retinoblastoma (RB) is the malignant neoplasm of embryonic neural retinal cells and is the
most common intraocular tumor of childhood. Early diagnosis associated with modern
methods of treatment resulted in increased survival rate of patients with retinoblastoma.
However, in those cases whose diagnosis is delayed and in untreated cases, the disease is
invariably fatal. The knowledge of the molecular and histopathological features of
retinoblastomas can influence the choice of treatment and benefit the prognosis of these
tumors. Thus, the objectives of this study are to evaluate the main histopathological and
molecular characteristics of retinoblastomas, including the evaluation of p16, Ki67 and VEGF
protein expression, as well as the potential role of such molecules as prognostic markers in the
retinoblastomas. Fifty-seven cases of RB were evaluated in enucleated eyes at Hospital
Araújo Jorge, in Goiânia, in the period of 1998 to 2011. Clinical data were collected from the
respective medical files and the cases were reviewed for analysis of histopathological aspects.
The expression of Ki67, p16 and VEGF was assessed by immunohistochemistry, using
specific antibodies and a detection system associated with polymers. The results were
analyzed by descriptive statistics and categorical variables by chi-square test and Fisher exact
test, when necessary. Ki67 overexpression was observed in 28% of cases, characterizing the
retinoblastomas with high rate of cellular proliferation, while the p16 overexpression was
observed in 42% of retinoblastomas evaluated. Significant associations were observed
between the overexpression of these proteins and histopathological characteristics of worse
prognosis, including invasion of the optic nerve, choroid, sclera and anterior chamber of the
eye, as well as to a lower degree of cellular differentiation. VEGF expression was extensively
observed in all retinoblastoma cases, independent of the histopathological aspects of the
tumors. The associations observed in this study between tumor aggressive histopathological
aspects and Ki67 and p16 overexpression, indicate the use of these markers in determining the
prognosis of retinoblastomas. On the other hand, the high angiogenic potential of
retinoblastomas, translated by diffuse VEGF expression in all cases analyzed in this study,
raises new investigations on the use of anti-angiogenic drugs in the treatment of
retinoblastomas.
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SALUSTIANO, Luciana Ximenes. Fatores histopatológicos e moleculares em retinoblastomas enucleados. 2013. 64 f. Tese (Doutorado em Ciências da Saúde) - Universidade Federal de Goiás, Goiânia, 2013.