Metachronous tumor development in unilateral retinoblastoma

PURPOSE. A series of 205 retinoblastoma (RB) patients referred to the Depar tment of Ophthalmology at the University of Siena (Italy) was evaluated in order to assess the proportion of unilateral cases later developing tumors in the companion eye ("metachronous" bilateral retinobastoma) (MBRB). METHODS. The total number of unilaterally affected patients developing tumo rs in the fellow eye was recorded and the risk factors assessed for the dev elopment of asynchronous bilateral retinoblastoma, i.e., family history, tu mor multifocality and early age at diagnosis. RESULTS. Only two out of 133 (1.5%) unilateral retinoblastoma patients in o ur series could be considered affected by MBRB. CONCLUSIONS. The incidence of MBRB in our series was negligible (1.5% of al l unilateral cases) compared to other reports. None of the reported risk fa ctors for the development of tumors in the fellow eye was relevant in the p resent series. Although close follow-up of some unilateral cases is still r ecommended, thorough examination of the fellow eye, to search for lesions i n the peripheral retina, is essential in all cases of unilateral RE. MBRB m ay be a distinctive clinical entity with specific clinical, genetic and pro gnostic features. However, all these aspects need to be better investigated in larger series.