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Immunohistochemical Analysis of Multidrug Resistance Protein-1 (MDR-1) / 1. Sumita Sethi1 1Pediatric ophthalmology, Oculoplasty and Oncology Services, Dr.R.P.Centre for Ophthalmic Sciences, AIIMS, New Delhi, India Background: Retinoblastoma is the most common primary intraocular malignancy in children. Currently chemotherapy is regarded as the mainstay of globe preserving treatments in intraocular retinoblastoma. In various systemic malignancies like neuroblastoma, high P-gp expression has been associated with poor prognosis. We investigated the immunohistochemical expression of P-gp in eyes with retinoblastoma and correlated with the histopathological Method: Haematoxylin and eosin stained sections from eyes enucleated over a 1 year period from January 2009 to December 2009 were evaluated for histopathological features (tumour differentiation and presence of high risk features). P -gp immunostaining was performed and graded semiquantatively as negative, low or high. Results: There were a total of 51 eyes, 40 enucleated as primary treatment for advanced intraocular retinoblastoma (group-I) and 11 postchemotherapy (group-II). High P -gp expression was noted in 4/40 (10%) cases in group-I as compared to 6/11 (54.5%) in group-II; the difference was statistically significant (p=0.0041). At the last known follow -up, one child in Conclusion: In retinoblastoma cases who had received chemotherapy, Pgp was highly expressed, of which 1 had orbital relapse. This expression might have been induced by chemotherapy or it may possibly play a role in chemoresistance. More prospective studies with a longer follow up are required to understand its clinical implications. Till then these children have |
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