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P53 Tumour Suppressor Gene in Retinoblastoma: An Immunohistochemical 1. Sumita Sethi¹ ¹Pediatric ophthalmology, Oculoplasty and Oncology Services, Dr.R.P.Centre for Ophthalmic Sciences, AIIMS, New Delhi, India Purpose: Retinoblastoma is the most common primary intraocular malignancy in children. Animal experiments have shown that loss of activity of the RB gene as well as the p53 gene (a tumour suppressor gene located on chromosome-17) is required for development of malignancy. We analysed immunohistochemical expression of p53 in human eyes enucleated as a primary treatment for advanced intraocular retinoblastoma. Method: Formalin fixed paraffin embedded sections from eyes enucleated as primary treatment for advanced intraocular retinoblastoma over a 1 year period from January 2009 to December 2009 were subjected to p53 immunohistochemical staining. Demographic data, tumour differentiation and high risk histopathological features (HRFs) were evaluated and analysed. Results: There were a total of 49 eyes, of which 41 (83.7%) had poorly differentiated and 8 (16.3%) had well differentiated tumours. Thirty one eyes (63.3%) had presence of HRFs. P53 expression was observed in 17/49 (34.7%) cases, of which 4 (8.2%) were strongly positive. There was no correlation between p53 expression and tumour differentiation and HRF. Conclusion: Expression of p53 has been associated with function of RB1, which is the main genetic defect in retinoblastoma. In our study, p53 was expressed in approximately 1/3rd of eyes enucleated for advanced intraocular retinoblastoma. This expression may not be associated with the pathogenesis of primary retinoblastoma but in long term follow-up, there could be a difference in behavior of the 2 groups. More number of prospective studies in correlation with long term follow-up will help in understanding the clinical significance of this finding. |
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