Retinoblasma: Incidence and Etiologic Factors

Although the molecular etiology of retinoblastoma is well understood, our knowledge of the role of the underlying risk and origin of the events leading to a lack of functional pRb remains limited, though more recent findings suggest intriguing aspects to examine further. Our understanding of the role of environmental exposures during retinal development, though preliminary, appears to suggest a greater role during early eye development. We present global incidence organized by UN-defined regions using data from the recent IARC Incidence of Childhood Cancer, with additional examination of subgroup variation in places where this data has been publicly shared. The international variation in incidence suggests that non-genetic risk factors for the development of retinoblastoma may exist. Recent studies have focused on exposures occurring during critical time periods (before or after conception) and individuals at risk (father vs. mother or child) for initiation of sporadic heritable and non-heritable retinoblastoma. Other studies have used cross-linked pollution indices, cancer registry, and birth registry data to examine the role of environmental exposures. Epidemiological studies have generally not yet considered our growing understanding of molecular variations in Rb, but our growing understanding of the chronology of the evolution of the disease confirms the relevance of the epidemiologic approaches to examine risk factors that may act during the critical time periods in disease evolution in individuals at risk. Epidemiologic studies can improve our understanding of disease development, risk factors, and potential strategies for prevention or for more effective treatment of retinoblastoma.