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For the past decades, the survival of retinoblastoma has been >80-90% in developed countries. 1 As opposed to most other malignancies, these excellent results may be more related to early diagnosis than to the availability of sophisticated treatments. Despite 90% of children affected with retinoblastoma who live in less-developed countries (LDCs), the published literature from this region has received little attention. 2 The reasons for this are manyfold. A publication bias against retrospective studies showing negative results or from LDCs has been reported for other conditions. 3 In the case of retinoblastoma, the problem is further compounded by the lack of a prospective approach in many treatment centres as well as lack of a staging system for extraocular disease. 4 Therefore, we speculated that relevant information about retinoblastoma outcome in LDCs may be available in languages other than English and published only in regional journals or as abstracts for specialised meetings.
Therefore, the aims of this study were to perform a systematic review of retinoblastoma literature from LDCs, carry out an analysis of the retrieved data and describe the outcome of those patients. Early diagnosis of retinoblastoma is influenced by socioeconomic and maternal educational factors, 5 so we speculated that indicators of childhood and maternal health could affect the outcome of retinoblastoma in LDCs. Thus, for this study, we also sought to identify the socioeconomic factors that potentially correlate with outcome.
Methods
Search strategy
We searched the PubMed database at http://www.ncbi.nlm.nih.gov/pubmed/using the terms "Retinoblastoma AND (Humans(Mesh)) AND ((infant(MeSH) OR child(MeSH) OR adolescent(MeSH))))" and retrieved publications from January 1998 to December 2008. Countries classified as low-income (LICs; gross national income (GNI) <US$755), and middle-income (MICs); which are further subdivided into upper-MICs (GNI US$2996-9265) and lower-MICs (GNI US$756-2995), per the World Bank ( http://web.worldbank.org/WBSITE/EXTERNAL/DATASTATISTICS/0,contentMDK:20420458∼menuPK:64133156∼pagePK:64133150∼piPK:64133175∼theSitePK:239419,00.html ) report of economies for the year 2000 were eligible. The abstracts of all publications from the eligible countries were screened and analysed by two authors (SC and GC).
Papers dealing with clinical features, treatment results, epidemiological studies and prevention or early diagnosis of retinoblastoma were eligible for this study, and the entire paper was analysed. Additional data were retrieved using the same strategy and time intervals at the following electronic data bases: EMBASE ( http://www.embase.com ), Literatura Latinoamericana y del Caribe...